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INFO-DIR-SECTION Software development
START-INFO-DIR-ENTRY
* gfortran: (gfortran). The GNU Fortran Compiler.
END-INFO-DIR-ENTRY
This file documents the use and the internals of the GNU Fortran
compiler, (`gfortran').
Published by the Free Software Foundation 51 Franklin Street, Fifth
Floor Boston, MA 02110-1301 USA
Copyright (C) 1999-2019 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with the
Invariant Sections being "Funding Free Software", the Front-Cover Texts
being (a) (see below), and with the Back-Cover Texts being (b) (see
below). A copy of the license is included in the section entitled "GNU
Free Documentation License".
(a) The FSF's Front-Cover Text is:
A GNU Manual
(b) The FSF's Back-Cover Text is:
You have freedom to copy and modify this GNU Manual, like GNU
software. Copies published by the Free Software Foundation raise
funds for GNU development.

File: gfortran.info, Node: Top, Next: Introduction, Up: (dir)
Introduction
************
This manual documents the use of `gfortran', the GNU Fortran compiler.
You can find in this manual how to invoke `gfortran', as well as its
features and incompatibilities.
* Menu:
* Introduction::
Part I: Invoking GNU Fortran
* Invoking GNU Fortran:: Command options supported by `gfortran'.
* Runtime:: Influencing runtime behavior with environment variables.
Part II: Language Reference
* Fortran standards status:: Fortran 2003, 2008 and 2018 features supported by GNU Fortran.
* Compiler Characteristics:: User-visible implementation details.
* Extensions:: Language extensions implemented by GNU Fortran.
* Mixed-Language Programming:: Interoperability with C
* Coarray Programming::
* Intrinsic Procedures:: Intrinsic procedures supported by GNU Fortran.
* Intrinsic Modules:: Intrinsic modules supported by GNU Fortran.
* Contributing:: How you can help.
* Copying:: GNU General Public License says
how you can copy and share GNU Fortran.
* GNU Free Documentation License::
How you can copy and share this manual.
* Funding:: How to help assure continued work for free software.
* Option Index:: Index of command line options
* Keyword Index:: Index of concepts

File: gfortran.info, Node: Introduction, Next: Invoking GNU Fortran, Prev: Top, Up: Top
1 Introduction
**************
The GNU Fortran compiler front end was designed initially as a free
replacement for, or alternative to, the Unix `f95' command; `gfortran'
is the command you will use to invoke the compiler.
* Menu:
* About GNU Fortran:: What you should know about the GNU Fortran compiler.
* GNU Fortran and GCC:: You can compile Fortran, C, or other programs.
* Preprocessing and conditional compilation:: The Fortran preprocessor
* GNU Fortran and G77:: Why we chose to start from scratch.
* Project Status:: Status of GNU Fortran, roadmap, proposed extensions.
* Standards:: Standards supported by GNU Fortran.

File: gfortran.info, Node: About GNU Fortran, Next: GNU Fortran and GCC, Up: Introduction
1.1 About GNU Fortran
=====================
The GNU Fortran compiler supports the Fortran 77, 90 and 95 standards
completely, parts of the Fortran 2003, 2008 and 2018 standards, and
several vendor extensions. The development goal is to provide the
following features:
* Read a user's program, stored in a file and containing instructions
written in Fortran 77, Fortran 90, Fortran 95, Fortran 2003,
Fortran 2008 or Fortran 2018. This file contains "source code".
* Translate the user's program into instructions a computer can
carry out more quickly than it takes to translate the instructions
in the first place. The result after compilation of a program is
"machine code", code designed to be efficiently translated and
processed by a machine such as your computer. Humans usually are
not as good writing machine code as they are at writing Fortran
(or C++, Ada, or Java), because it is easy to make tiny mistakes
writing machine code.
* Provide the user with information about the reasons why the
compiler is unable to create a binary from the source code.
Usually this will be the case if the source code is flawed. The
Fortran 90 standard requires that the compiler can point out
mistakes to the user. An incorrect usage of the language causes
an "error message".
The compiler will also attempt to diagnose cases where the user's
program contains a correct usage of the language, but instructs
the computer to do something questionable. This kind of
diagnostics message is called a "warning message".
* Provide optional information about the translation passes from the
source code to machine code. This can help a user of the compiler
to find the cause of certain bugs which may not be obvious in the
source code, but may be more easily found at a lower level
compiler output. It also helps developers to find bugs in the
compiler itself.
* Provide information in the generated machine code that can make it
easier to find bugs in the program (using a debugging tool, called
a "debugger", such as the GNU Debugger `gdb').
* Locate and gather machine code already generated to perform
actions requested by statements in the user's program. This
machine code is organized into "modules" and is located and
"linked" to the user program.
The GNU Fortran compiler consists of several components:
* A version of the `gcc' command (which also might be installed as
the system's `cc' command) that also understands and accepts
Fortran source code. The `gcc' command is the "driver" program for
all the languages in the GNU Compiler Collection (GCC); With `gcc',
you can compile the source code of any language for which a front
end is available in GCC.
* The `gfortran' command itself, which also might be installed as the
system's `f95' command. `gfortran' is just another driver program,
but specifically for the Fortran compiler only. The difference
with `gcc' is that `gfortran' will automatically link the correct
libraries to your program.
* A collection of run-time libraries. These libraries contain the
machine code needed to support capabilities of the Fortran
language that are not directly provided by the machine code
generated by the `gfortran' compilation phase, such as intrinsic
functions and subroutines, and routines for interaction with files
and the operating system.
* The Fortran compiler itself, (`f951'). This is the GNU Fortran
parser and code generator, linked to and interfaced with the GCC
backend library. `f951' "translates" the source code to assembler
code. You would typically not use this program directly; instead,
the `gcc' or `gfortran' driver programs will call it for you.

File: gfortran.info, Node: GNU Fortran and GCC, Next: Preprocessing and conditional compilation, Prev: About GNU Fortran, Up: Introduction
1.2 GNU Fortran and GCC
=======================
GNU Fortran is a part of GCC, the "GNU Compiler Collection". GCC
consists of a collection of front ends for various languages, which
translate the source code into a language-independent form called
"GENERIC". This is then processed by a common middle end which
provides optimization, and then passed to one of a collection of back
ends which generate code for different computer architectures and
operating systems.
Functionally, this is implemented with a driver program (`gcc')
which provides the command-line interface for the compiler. It calls
the relevant compiler front-end program (e.g., `f951' for Fortran) for
each file in the source code, and then calls the assembler and linker
as appropriate to produce the compiled output. In a copy of GCC which
has been compiled with Fortran language support enabled, `gcc' will
recognize files with `.f', `.for', `.ftn', `.f90', `.f95', `.f03' and
`.f08' extensions as Fortran source code, and compile it accordingly.
A `gfortran' driver program is also provided, which is identical to
`gcc' except that it automatically links the Fortran runtime libraries
into the compiled program.
Source files with `.f', `.for', `.fpp', `.ftn', `.F', `.FOR',
`.FPP', and `.FTN' extensions are treated as fixed form. Source files
with `.f90', `.f95', `.f03', `.f08', `.F90', `.F95', `.F03' and `.F08'
extensions are treated as free form. The capitalized versions of
either form are run through preprocessing. Source files with the lower
case `.fpp' extension are also run through preprocessing.
This manual specifically documents the Fortran front end, which
handles the programming language's syntax and semantics. The aspects
of GCC which relate to the optimization passes and the back-end code
generation are documented in the GCC manual; see *note Introduction:
(gcc)Top. The two manuals together provide a complete reference for
the GNU Fortran compiler.

File: gfortran.info, Node: Preprocessing and conditional compilation, Next: GNU Fortran and G77, Prev: GNU Fortran and GCC, Up: Introduction
1.3 Preprocessing and conditional compilation
=============================================
Many Fortran compilers including GNU Fortran allow passing the source
code through a C preprocessor (CPP; sometimes also called the Fortran
preprocessor, FPP) to allow for conditional compilation. In the case
of GNU Fortran, this is the GNU C Preprocessor in the traditional mode.
On systems with case-preserving file names, the preprocessor is
automatically invoked if the filename extension is `.F', `.FOR',
`.FTN', `.fpp', `.FPP', `.F90', `.F95', `.F03' or `.F08'. To manually
invoke the preprocessor on any file, use `-cpp', to disable
preprocessing on files where the preprocessor is run automatically, use
`-nocpp'.
If a preprocessed file includes another file with the Fortran
`INCLUDE' statement, the included file is not preprocessed. To
preprocess included files, use the equivalent preprocessor statement
`#include'.
If GNU Fortran invokes the preprocessor, `__GFORTRAN__' is defined.
The macros `__GNUC__', `__GNUC_MINOR__' and `__GNUC_PATCHLEVEL__' can
be used to determine the version of the compiler. See *note Overview:
(cpp)Top. for details.
GNU Fortran supports a number of `INTEGER' and `REAL' kind types in
additional to the kind types required by the Fortran standard. The
availability of any given kind type is architecture dependent. The
following pre-defined preprocessor macros can be used to conditionally
include code for these additional kind types: `__GFC_INT_1__',
`__GFC_INT_2__', `__GFC_INT_8__', `__GFC_INT_16__', `__GFC_REAL_10__',
and `__GFC_REAL_16__'.
While CPP is the de-facto standard for preprocessing Fortran code,
Part 3 of the Fortran 95 standard (ISO/IEC 1539-3:1998) defines
Conditional Compilation, which is not widely used and not directly
supported by the GNU Fortran compiler. You can use the program coco to
preprocess such files (`http://www.daniellnagle.com/coco.html').

File: gfortran.info, Node: GNU Fortran and G77, Next: Project Status, Prev: Preprocessing and conditional compilation, Up: Introduction
1.4 GNU Fortran and G77
=======================
The GNU Fortran compiler is the successor to `g77', the Fortran 77
front end included in GCC prior to version 4. It is an entirely new
program that has been designed to provide Fortran 95 support and
extensibility for future Fortran language standards, as well as
providing backwards compatibility for Fortran 77 and nearly all of the
GNU language extensions supported by `g77'.

File: gfortran.info, Node: Project Status, Next: Standards, Prev: GNU Fortran and G77, Up: Introduction
1.5 Project Status
==================
As soon as `gfortran' can parse all of the statements correctly,
it will be in the "larva" state. When we generate code, the
"puppa" state. When `gfortran' is done, we'll see if it will be a
beautiful butterfly, or just a big bug....
-Andy Vaught, April 2000
The start of the GNU Fortran 95 project was announced on the GCC
homepage in March 18, 2000 (even though Andy had already been working
on it for a while, of course).
The GNU Fortran compiler is able to compile nearly all
standard-compliant Fortran 95, Fortran 90, and Fortran 77 programs,
including a number of standard and non-standard extensions, and can be
used on real-world programs. In particular, the supported extensions
include OpenMP, Cray-style pointers, some old vendor extensions, and
several Fortran 2003 and Fortran 2008 features, including TR 15581.
However, it is still under development and has a few remaining rough
edges. There also is initial support for OpenACC. Note that this is
an experimental feature, incomplete, and subject to change in future
versions of GCC. See `https://gcc.gnu.org/wiki/OpenACC' for more
information.
At present, the GNU Fortran compiler passes the NIST Fortran 77 Test
Suite (http://www.fortran-2000.com/ArnaudRecipes/fcvs21_f95.html), and
produces acceptable results on the LAPACK Test Suite
(http://www.netlib.org/lapack/faq.html#1.21). It also provides
respectable performance on the Polyhedron Fortran compiler benchmarks
(http://www.polyhedron.com/fortran-compiler-comparisons/polyhedron-benchmark-suite)
and the Livermore Fortran Kernels test
(http://www.netlib.org/benchmark/livermore). It has been used to
compile a number of large real-world programs, including the HARMONIE
and HIRLAM weather forecasting code (http://hirlam.org/) and the Tonto
quantum chemistry package
(http://physical-chemistry.scb.uwa.edu.au/tonto/wiki/index.php/Main_Page);
see `https://gcc.gnu.org/wiki/GfortranApps' for an extended list.
Among other things, the GNU Fortran compiler is intended as a
replacement for G77. At this point, nearly all programs that could be
compiled with G77 can be compiled with GNU Fortran, although there are
a few minor known regressions.
The primary work remaining to be done on GNU Fortran falls into three
categories: bug fixing (primarily regarding the treatment of invalid
code and providing useful error messages), improving the compiler
optimizations and the performance of compiled code, and extending the
compiler to support future standards--in particular, Fortran 2003,
Fortran 2008 and Fortran 2018.

File: gfortran.info, Node: Standards, Prev: Project Status, Up: Introduction
1.6 Standards
=============
* Menu:
* Varying Length Character Strings::
The GNU Fortran compiler implements ISO/IEC 1539:1997 (Fortran 95).
As such, it can also compile essentially all standard-compliant Fortran
90 and Fortran 77 programs. It also supports the ISO/IEC TR-15581
enhancements to allocatable arrays.
GNU Fortran also have a partial support for ISO/IEC 1539-1:2004
(Fortran 2003), ISO/IEC 1539-1:2010 (Fortran 2008), the Technical
Specification `Further Interoperability of Fortran with C' (ISO/IEC TS
29113:2012). Full support of those standards and future Fortran
standards is planned. The current status of the support is can be
found in the *note Fortran 2003 status::, *note Fortran 2008 status::
and *note Fortran 2018 status:: sections of the documentation.
Additionally, the GNU Fortran compilers supports the OpenMP
specification (version 4.0 and most of the features of the 4.5 version,
`http://openmp.org/wp/openmp-specifications/'). There also is initial
support for the OpenACC specification (targeting version 2.0,
`http://www.openacc.org/'). Note that this is an experimental feature,
incomplete, and subject to change in future versions of GCC. See
`https://gcc.gnu.org/wiki/OpenACC' for more information.

File: gfortran.info, Node: Varying Length Character Strings, Up: Standards
1.6.1 Varying Length Character Strings
--------------------------------------
The Fortran 95 standard specifies in Part 2 (ISO/IEC 1539-2:2000)
varying length character strings. While GNU Fortran currently does not
support such strings directly, there exist two Fortran implementations
for them, which work with GNU Fortran. They can be found at
`http://www.fortran.com/iso_varying_string.f95' and at
`ftp://ftp.nag.co.uk/sc22wg5/ISO_VARYING_STRING/'.
Deferred-length character strings of Fortran 2003 supports part of
the features of `ISO_VARYING_STRING' and should be considered as
replacement. (Namely, allocatable or pointers of the type
`character(len=:)'.)

File: gfortran.info, Node: Invoking GNU Fortran, Next: Runtime, Prev: Introduction, Up: Top
2 GNU Fortran Command Options
*****************************
The `gfortran' command supports all the options supported by the `gcc'
command. Only options specific to GNU Fortran are documented here.
*Note GCC Command Options: (gcc)Invoking GCC, for information on the
non-Fortran-specific aspects of the `gcc' command (and, therefore, the
`gfortran' command).
All GCC and GNU Fortran options are accepted both by `gfortran' and
by `gcc' (as well as any other drivers built at the same time, such as
`g++'), since adding GNU Fortran to the GCC distribution enables
acceptance of GNU Fortran options by all of the relevant drivers.
In some cases, options have positive and negative forms; the
negative form of `-ffoo' would be `-fno-foo'. This manual documents
only one of these two forms, whichever one is not the default.
* Menu:
* Option Summary:: Brief list of all `gfortran' options,
without explanations.
* Fortran Dialect Options:: Controlling the variant of Fortran language
compiled.
* Preprocessing Options:: Enable and customize preprocessing.
* Error and Warning Options:: How picky should the compiler be?
* Debugging Options:: Symbol tables, measurements, and debugging dumps.
* Directory Options:: Where to find module files
* Link Options :: Influencing the linking step
* Runtime Options:: Influencing runtime behavior
* Code Gen Options:: Specifying conventions for function calls, data layout
and register usage.
* Interoperability Options:: Options for interoperability with other
languages.
* Environment Variables:: Environment variables that affect `gfortran'.

File: gfortran.info, Node: Option Summary, Next: Fortran Dialect Options, Up: Invoking GNU Fortran
2.1 Option summary
==================
Here is a summary of all the options specific to GNU Fortran, grouped
by type. Explanations are in the following sections.
_Fortran Language Options_
*Note Options controlling Fortran dialect: Fortran Dialect Options.
-fall-intrinsics -fbackslash -fcray-pointer -fd-lines-as-code
-fd-lines-as-comments
-fdec -fdec-structure -fdec-intrinsic-ints -fdec-static -fdec-math
-fdec-include -fdefault-double-8 -fdefault-integer-8 -fdefault-real-8
-fdefault-real-10 -fdefault-real-16 -fdollar-ok -ffixed-line-length-N
-ffixed-line-length-none -fpad-source -ffree-form -ffree-line-length-N
-ffree-line-length-none -fimplicit-none -finteger-4-integer-8
-fmax-identifier-length -fmodule-private -ffixed-form -fno-range-check
-fopenacc -fopenmp -freal-4-real-10 -freal-4-real-16 -freal-4-real-8
-freal-8-real-10 -freal-8-real-16 -freal-8-real-4 -std=STD
-ftest-forall-temp
_Preprocessing Options_
*Note Enable and customize preprocessing: Preprocessing Options.
-A-QUESTION[=ANSWER]
-AQUESTION=ANSWER -C -CC -DMACRO[=DEFN]
-H -P
-UMACRO -cpp -dD -dI -dM -dN -dU -fworking-directory
-imultilib DIR
-iprefix FILE -iquote -isysroot DIR -isystem DIR -nocpp
-nostdinc
-undef
_Error and Warning Options_
*Note Options to request or suppress errors and warnings: Error
and Warning Options.
-Waliasing -Wall -Wampersand -Wargument-mismatch -Warray-bounds
-Wc-binding-type -Wcharacter-truncation -Wconversion
-Wdo-subscript -Wfunction-elimination -Wimplicit-interface
-Wimplicit-procedure -Wintrinsic-shadow -Wuse-without-only -Wintrinsics-std
-Wline-truncation -Wno-align-commons -Wno-tabs -Wreal-q-constant
-Wsurprising -Wunderflow -Wunused-parameter -Wrealloc-lhs
-Wrealloc-lhs-all -Wfrontend-loop-interchange -Wtarget-lifetime
-fmax-errors=N -fsyntax-only -pedantic -pedantic-errors
_Debugging Options_
*Note Options for debugging your program or GNU Fortran: Debugging
Options.
-fbacktrace -fdump-fortran-optimized -fdump-fortran-original
-fdump-fortran-global -fdump-parse-tree -ffpe-trap=LIST
-ffpe-summary=LIST
_Directory Options_
*Note Options for directory search: Directory Options.
-IDIR -JDIR -fintrinsic-modules-path DIR
_Link Options_
*Note Options for influencing the linking step: Link Options.
-static-libgfortran
_Runtime Options_
*Note Options for influencing runtime behavior: Runtime Options.
-fconvert=CONVERSION -fmax-subrecord-length=LENGTH
-frecord-marker=LENGTH -fsign-zero
_Interoperability Options_
*Note Options for interoperability: Interoperability Options.
-fc-prototypes -fc-prototypes-external
_Code Generation Options_
*Note Options for code generation conventions: Code Gen Options.
-faggressive-function-elimination -fblas-matmul-limit=N
-fbounds-check -ftail-call-workaround -ftail-call-workaround=N
-fcheck-array-temporaries
-fcheck=<ALL|ARRAY-TEMPS|BOUNDS|DO|MEM|POINTER|RECURSION>
-fcoarray=<NONE|SINGLE|LIB> -fexternal-blas -ff2c
-ffrontend-loop-interchange
-ffrontend-optimize
-finit-character=N -finit-integer=N -finit-local-zero
-finit-derived
-finit-logical=<TRUE|FALSE>
-finit-real=<ZERO|INF|-INF|NAN|SNAN>
-finline-matmul-limit=N
-fmax-array-constructor=N -fmax-stack-var-size=N
-fno-align-commons
-fno-automatic -fno-protect-parens -fno-underscoring
-fsecond-underscore -fpack-derived -frealloc-lhs -frecursive
-frepack-arrays -fshort-enums -fstack-arrays

File: gfortran.info, Node: Fortran Dialect Options, Next: Preprocessing Options, Prev: Option Summary, Up: Invoking GNU Fortran
2.2 Options controlling Fortran dialect
=======================================
The following options control the details of the Fortran dialect
accepted by the compiler:
`-ffree-form'
`-ffixed-form'
Specify the layout used by the source file. The free form layout
was introduced in Fortran 90. Fixed form was traditionally used in
older Fortran programs. When neither option is specified, the
source form is determined by the file extension.
`-fall-intrinsics'
This option causes all intrinsic procedures (including the
GNU-specific extensions) to be accepted. This can be useful with
`-std=f95' to force standard-compliance but get access to the full
range of intrinsics available with `gfortran'. As a consequence,
`-Wintrinsics-std' will be ignored and no user-defined procedure
with the same name as any intrinsic will be called except when it
is explicitly declared `EXTERNAL'.
`-fd-lines-as-code'
`-fd-lines-as-comments'
Enable special treatment for lines beginning with `d' or `D' in
fixed form sources. If the `-fd-lines-as-code' option is given
they are treated as if the first column contained a blank. If the
`-fd-lines-as-comments' option is given, they are treated as
comment lines.
`-fdec'
DEC compatibility mode. Enables extensions and other features that
mimic the default behavior of older compilers (such as DEC).
These features are non-standard and should be avoided at all costs.
For details on GNU Fortran's implementation of these extensions
see the full documentation.
Other flags enabled by this switch are: `-fdollar-ok'
`-fcray-pointer' `-fdec-structure' `-fdec-intrinsic-ints'
`-fdec-static' `-fdec-math'
If `-fd-lines-as-code'/`-fd-lines-as-comments' are unset, then
`-fdec' also sets `-fd-lines-as-comments'.
`-fdec-structure'
Enable DEC `STRUCTURE' and `RECORD' as well as `UNION', `MAP', and
dot ('.') as a member separator (in addition to '%'). This is
provided for compatibility only; Fortran 90 derived types should
be used instead where possible.
`-fdec-intrinsic-ints'
Enable B/I/J/K kind variants of existing integer functions (e.g.
BIAND, IIAND, JIAND, etc...). For a complete list of intrinsics
see the full documentation.
`-fdec-math'
Enable legacy math intrinsics such as COTAN and degree-valued
trigonometric functions (e.g. TAND, ATAND, etc...) for
compatability with older code.
`-fdec-static'
Enable DEC-style STATIC and AUTOMATIC attributes to explicitly
specify the storage of variables and other objects.
`-fdec-include'
Enable parsing of INCLUDE as a statement in addition to parsing it
as INCLUDE line. When parsed as INCLUDE statement, INCLUDE does
not have to be on a single line and can use line continuations.
`-fdollar-ok'
Allow `$' as a valid non-first character in a symbol name. Symbols
that start with `$' are rejected since it is unclear which rules to
apply to implicit typing as different vendors implement different
rules. Using `$' in `IMPLICIT' statements is also rejected.
`-fbackslash'
Change the interpretation of backslashes in string literals from a
single backslash character to "C-style" escape characters. The
following combinations are expanded `\a', `\b', `\f', `\n', `\r',
`\t', `\v', `\\', and `\0' to the ASCII characters alert,
backspace, form feed, newline, carriage return, horizontal tab,
vertical tab, backslash, and NUL, respectively. Additionally,
`\x'NN, `\u'NNNN and `\U'NNNNNNNN (where each N is a hexadecimal
digit) are translated into the Unicode characters corresponding to
the specified code points. All other combinations of a character
preceded by \ are unexpanded.
`-fmodule-private'
Set the default accessibility of module entities to `PRIVATE'.
Use-associated entities will not be accessible unless they are
explicitly declared as `PUBLIC'.
`-ffixed-line-length-N'
Set column after which characters are ignored in typical fixed-form
lines in the source file, and, unless `-fno-pad-source', through
which spaces are assumed (as if padded to that length) after the
ends of short fixed-form lines.
Popular values for N include 72 (the standard and the default), 80
(card image), and 132 (corresponding to "extended-source" options
in some popular compilers). N may also be `none', meaning that
the entire line is meaningful and that continued character
constants never have implicit spaces appended to them to fill out
the line. `-ffixed-line-length-0' means the same thing as
`-ffixed-line-length-none'.
`-fno-pad-source'
By default fixed-form lines have spaces assumed (as if padded to
that length) after the ends of short fixed-form lines. This is
not done either if `-ffixed-line-length-0',
`-ffixed-line-length-none' or if `-fno-pad-source' option is used.
With any of those options continued character constants never have
implicit spaces appended to them to fill out the line.
`-ffree-line-length-N'
Set column after which characters are ignored in typical free-form
lines in the source file. The default value is 132. N may be
`none', meaning that the entire line is meaningful.
`-ffree-line-length-0' means the same thing as
`-ffree-line-length-none'.
`-fmax-identifier-length=N'
Specify the maximum allowed identifier length. Typical values are
31 (Fortran 95) and 63 (Fortran 2003 and Fortran 2008).
`-fimplicit-none'
Specify that no implicit typing is allowed, unless overridden by
explicit `IMPLICIT' statements. This is the equivalent of adding
`implicit none' to the start of every procedure.
`-fcray-pointer'
Enable the Cray pointer extension, which provides C-like pointer
functionality.
`-fopenacc'
Enable the OpenACC extensions. This includes OpenACC `!$acc'
directives in free form and `c$acc', `*$acc' and `!$acc'
directives in fixed form, `!$' conditional compilation sentinels
in free form and `c$', `*$' and `!$' sentinels in fixed form, and
when linking arranges for the OpenACC runtime library to be linked
in.
Note that this is an experimental feature, incomplete, and subject
to change in future versions of GCC. See
`https://gcc.gnu.org/wiki/OpenACC' for more information.
`-fopenmp'
Enable the OpenMP extensions. This includes OpenMP `!$omp'
directives in free form and `c$omp', `*$omp' and `!$omp'
directives in fixed form, `!$' conditional compilation sentinels
in free form and `c$', `*$' and `!$' sentinels in fixed form, and
when linking arranges for the OpenMP runtime library to be linked
in. The option `-fopenmp' implies `-frecursive'.
`-fno-range-check'
Disable range checking on results of simplification of constant
expressions during compilation. For example, GNU Fortran will give
an error at compile time when simplifying `a = 1. / 0'. With this
option, no error will be given and `a' will be assigned the value
`+Infinity'. If an expression evaluates to a value outside of the
relevant range of [`-HUGE()':`HUGE()'], then the expression will
be replaced by `-Inf' or `+Inf' as appropriate. Similarly, `DATA
i/Z'FFFFFFFF'/' will result in an integer overflow on most
systems, but with `-fno-range-check' the value will "wrap around"
and `i' will be initialized to -1 instead.
`-fdefault-integer-8'
Set the default integer and logical types to an 8 byte wide type.
This option also affects the kind of integer constants like `42'.
Unlike `-finteger-4-integer-8', it does not promote variables with
explicit kind declaration.
`-fdefault-real-8'
Set the default real type to an 8 byte wide type. This option
also affects the kind of non-double real constants like `1.0'.
This option promotes the default width of `DOUBLE PRECISION' and
double real constants like `1.d0' to 16 bytes if possible. If
`-fdefault-double-8' is given along with `fdefault-real-8',
`DOUBLE PRECISION' and double real constants are not promoted.
Unlike `-freal-4-real-8', `fdefault-real-8' does not promote
variables with explicit kind declarations.
`-fdefault-real-10'
Set the default real type to an 10 byte wide type. This option
also affects the kind of non-double real constants like `1.0'.
This option promotes the default width of `DOUBLE PRECISION' and
double real constants like `1.d0' to 16 bytes if possible. If
`-fdefault-double-8' is given along with `fdefault-real-10',
`DOUBLE PRECISION' and double real constants are not promoted.
Unlike `-freal-4-real-10', `fdefault-real-10' does not promote
variables with explicit kind declarations.
`-fdefault-real-16'
Set the default real type to an 16 byte wide type. This option
also affects the kind of non-double real constants like `1.0'.
This option promotes the default width of `DOUBLE PRECISION' and
double real constants like `1.d0' to 16 bytes if possible. If
`-fdefault-double-8' is given along with `fdefault-real-16',
`DOUBLE PRECISION' and double real constants are not promoted.
Unlike `-freal-4-real-16', `fdefault-real-16' does not promote
variables with explicit kind declarations.
`-fdefault-double-8'
Set the `DOUBLE PRECISION' type and double real constants like
`1.d0' to an 8 byte wide type. Do nothing if this is already the
default. This option prevents `-fdefault-real-8',
`-fdefault-real-10', and `-fdefault-real-16', from promoting
`DOUBLE PRECISION' and double real constants like `1.d0' to 16
bytes.
`-finteger-4-integer-8'
Promote all `INTEGER(KIND=4)' entities to an `INTEGER(KIND=8)'
entities. If `KIND=8' is unavailable, then an error will be
issued. This option should be used with care and may not be
suitable for your codes. Areas of possible concern include calls
to external procedures, alignment in `EQUIVALENCE' and/or
`COMMON', generic interfaces, BOZ literal constant conversion, and
I/O. Inspection of the intermediate representation of the
translated Fortran code, produced by `-fdump-tree-original', is
suggested.
`-freal-4-real-8'
`-freal-4-real-10'
`-freal-4-real-16'
`-freal-8-real-4'
`-freal-8-real-10'
`-freal-8-real-16'
Promote all `REAL(KIND=M)' entities to `REAL(KIND=N)' entities.
If `REAL(KIND=N)' is unavailable, then an error will be issued.
All other real kind types are unaffected by this option. These
options should be used with care and may not be suitable for your
codes. Areas of possible concern include calls to external
procedures, alignment in `EQUIVALENCE' and/or `COMMON', generic
interfaces, BOZ literal constant conversion, and I/O. Inspection
of the intermediate representation of the translated Fortran code,
produced by `-fdump-tree-original', is suggested.
`-std=STD'
Specify the standard to which the program is expected to conform,
which may be one of `f95', `f2003', `f2008', `f2018', `gnu', or
`legacy'. The default value for STD is `gnu', which specifies a
superset of the latest Fortran standard that includes all of the
extensions supported by GNU Fortran, although warnings will be
given for obsolete extensions not recommended for use in new code.
The `legacy' value is equivalent but without the warnings for
obsolete extensions, and may be useful for old non-standard
programs. The `f95', `f2003', `f2008', and `f2018' values specify
strict conformance to the Fortran 95, Fortran 2003, Fortran 2008
and Fortran 2018 standards, respectively; errors are given for all
extensions beyond the relevant language standard, and warnings are
given for the Fortran 77 features that are permitted but
obsolescent in later standards. The deprecated option
`-std=f2008ts' acts as an alias for `-std=f2018'. It is only
present for backwards compatibility with earlier gfortran versions
and should not be used any more.
`-ftest-forall-temp'
Enhance test coverage by forcing most forall assignments to use
temporary.

File: gfortran.info, Node: Preprocessing Options, Next: Error and Warning Options, Prev: Fortran Dialect Options, Up: Invoking GNU Fortran
2.3 Enable and customize preprocessing
======================================
Preprocessor related options. See section *note Preprocessing and
conditional compilation:: for more detailed information on
preprocessing in `gfortran'.
`-cpp'
`-nocpp'
Enable preprocessing. The preprocessor is automatically invoked if
the file extension is `.fpp', `.FPP', `.F', `.FOR', `.FTN',
`.F90', `.F95', `.F03' or `.F08'. Use this option to manually
enable preprocessing of any kind of Fortran file.
To disable preprocessing of files with any of the above listed
extensions, use the negative form: `-nocpp'.
The preprocessor is run in traditional mode. Any restrictions of
the file-format, especially the limits on line length, apply for
preprocessed output as well, so it might be advisable to use the
`-ffree-line-length-none' or `-ffixed-line-length-none' options.
`-dM'
Instead of the normal output, generate a list of `'#define''
directives for all the macros defined during the execution of the
preprocessor, including predefined macros. This gives you a way of
finding out what is predefined in your version of the preprocessor.
Assuming you have no file `foo.f90', the command
touch foo.f90; gfortran -cpp -E -dM foo.f90
will show all the predefined macros.
`-dD'
Like `-dM' except in two respects: it does not include the
predefined macros, and it outputs both the `#define' directives
and the result of preprocessing. Both kinds of output go to the
standard output file.
`-dN'
Like `-dD', but emit only the macro names, not their expansions.
`-dU'
Like `dD' except that only macros that are expanded, or whose
definedness is tested in preprocessor directives, are output; the
output is delayed until the use or test of the macro; and
`'#undef'' directives are also output for macros tested but
undefined at the time.
`-dI'
Output `'#include'' directives in addition to the result of
preprocessing.
`-fworking-directory'
Enable generation of linemarkers in the preprocessor output that
will let the compiler know the current working directory at the
time of preprocessing. When this option is enabled, the
preprocessor will emit, after the initial linemarker, a second
linemarker with the current working directory followed by two
slashes. GCC will use this directory, when it is present in the
preprocessed input, as the directory emitted as the current
working directory in some debugging information formats. This
option is implicitly enabled if debugging information is enabled,
but this can be inhibited with the negated form
`-fno-working-directory'. If the `-P' flag is present in the
command line, this option has no effect, since no `#line'
directives are emitted whatsoever.
`-idirafter DIR'
Search DIR for include files, but do it after all directories
specified with `-I' and the standard system directories have been
exhausted. DIR is treated as a system include directory. If dir
begins with `=', then the `=' will be replaced by the sysroot
prefix; see `--sysroot' and `-isysroot'.
`-imultilib DIR'
Use DIR as a subdirectory of the directory containing
target-specific C++ headers.
`-iprefix PREFIX'
Specify PREFIX as the prefix for subsequent `-iwithprefix'
options. If the PREFIX represents a directory, you should include
the final `'/''.
`-isysroot DIR'
This option is like the `--sysroot' option, but applies only to
header files. See the `--sysroot' option for more information.
`-iquote DIR'
Search DIR only for header files requested with `#include "file"';
they are not searched for `#include <file>', before all directories
specified by `-I' and before the standard system directories. If
DIR begins with `=', then the `=' will be replaced by the sysroot
prefix; see `--sysroot' and `-isysroot'.
`-isystem DIR'
Search DIR for header files, after all directories specified by
`-I' but before the standard system directories. Mark it as a
system directory, so that it gets the same special treatment as is
applied to the standard system directories. If DIR begins with
`=', then the `=' will be replaced by the sysroot prefix; see
`--sysroot' and `-isysroot'.
`-nostdinc'
Do not search the standard system directories for header files.
Only the directories you have specified with `-I' options (and the
directory of the current file, if appropriate) are searched.
`-undef'
Do not predefine any system-specific or GCC-specific macros. The
standard predefined macros remain defined.
`-APREDICATE=ANSWER'
Make an assertion with the predicate PREDICATE and answer ANSWER.
This form is preferred to the older form -A predicate(answer),
which is still supported, because it does not use shell special
characters.
`-A-PREDICATE=ANSWER'
Cancel an assertion with the predicate PREDICATE and answer ANSWER.
`-C'
Do not discard comments. All comments are passed through to the
output file, except for comments in processed directives, which
are deleted along with the directive.
You should be prepared for side effects when using `-C'; it causes
the preprocessor to treat comments as tokens in their own right.
For example, comments appearing at the start of what would be a
directive line have the effect of turning that line into an
ordinary source line, since the first token on the line is no
longer a `'#''.
Warning: this currently handles C-Style comments only. The
preprocessor does not yet recognize Fortran-style comments.
`-CC'
Do not discard comments, including during macro expansion. This is
like `-C', except that comments contained within macros are also
passed through to the output file where the macro is expanded.
In addition to the side-effects of the `-C' option, the `-CC'
option causes all C++-style comments inside a macro to be
converted to C-style comments. This is to prevent later use of
that macro from inadvertently commenting out the remainder of the
source line. The `-CC' option is generally used to support lint
comments.
Warning: this currently handles C- and C++-Style comments only. The
preprocessor does not yet recognize Fortran-style comments.
`-DNAME'
Predefine name as a macro, with definition `1'.
`-DNAME=DEFINITION'
The contents of DEFINITION are tokenized and processed as if they
appeared during translation phase three in a `'#define'' directive.
In particular, the definition will be truncated by embedded newline
characters.
If you are invoking the preprocessor from a shell or shell-like
program you may need to use the shell's quoting syntax to protect
characters such as spaces that have a meaning in the shell syntax.
If you wish to define a function-like macro on the command line,
write its argument list with surrounding parentheses before the
equals sign (if any). Parentheses are meaningful to most shells,
so you will need to quote the option. With sh and csh,
`-D'name(args...)=definition'' works.
`-D' and `-U' options are processed in the order they are given on
the command line. All -imacros file and -include file options are
processed after all -D and -U options.
`-H'
Print the name of each header file used, in addition to other
normal activities. Each name is indented to show how deep in the
`'#include'' stack it is.
`-P'
Inhibit generation of linemarkers in the output from the
preprocessor. This might be useful when running the preprocessor
on something that is not C code, and will be sent to a program
which might be confused by the linemarkers.
`-UNAME'
Cancel any previous definition of NAME, either built in or provided
with a `-D' option.

File: gfortran.info, Node: Error and Warning Options, Next: Debugging Options, Prev: Preprocessing Options, Up: Invoking GNU Fortran
2.4 Options to request or suppress errors and warnings
======================================================
Errors are diagnostic messages that report that the GNU Fortran compiler
cannot compile the relevant piece of source code. The compiler will
continue to process the program in an attempt to report further errors
to aid in debugging, but will not produce any compiled output.
Warnings are diagnostic messages that report constructions which are
not inherently erroneous but which are risky or suggest there is likely
to be a bug in the program. Unless `-Werror' is specified, they do not
prevent compilation of the program.
You can request many specific warnings with options beginning `-W',
for example `-Wimplicit' to request warnings on implicit declarations.
Each of these specific warning options also has a negative form
beginning `-Wno-' to turn off warnings; for example, `-Wno-implicit'.
This manual lists only one of the two forms, whichever is not the
default.
These options control the amount and kinds of errors and warnings
produced by GNU Fortran:
`-fmax-errors=N'
Limits the maximum number of error messages to N, at which point
GNU Fortran bails out rather than attempting to continue
processing the source code. If N is 0, there is no limit on the
number of error messages produced.
`-fsyntax-only'
Check the code for syntax errors, but do not actually compile it.
This will generate module files for each module present in the
code, but no other output file.
`-Wpedantic'
`-pedantic'
Issue warnings for uses of extensions to Fortran. `-pedantic'
also applies to C-language constructs where they occur in GNU
Fortran source files, such as use of `\e' in a character constant
within a directive like `#include'.
Valid Fortran programs should compile properly with or without
this option. However, without this option, certain GNU extensions
and traditional Fortran features are supported as well. With this
option, many of them are rejected.
Some users try to use `-pedantic' to check programs for
conformance. They soon find that it does not do quite what they
want--it finds some nonstandard practices, but not all. However,
improvements to GNU Fortran in this area are welcome.
This should be used in conjunction with `-std=f95', `-std=f2003',
`-std=f2008' or `-std=f2018'.
`-pedantic-errors'
Like `-pedantic', except that errors are produced rather than
warnings.
`-Wall'
Enables commonly used warning options pertaining to usage that we
recommend avoiding and that we believe are easy to avoid. This
currently includes `-Waliasing', `-Wampersand', `-Wconversion',
`-Wsurprising', `-Wc-binding-type', `-Wintrinsics-std', `-Wtabs',
`-Wintrinsic-shadow', `-Wline-truncation', `-Wtarget-lifetime',
`-Winteger-division', `-Wreal-q-constant', `-Wunused' and
`-Wundefined-do-loop'.
`-Waliasing'
Warn about possible aliasing of dummy arguments. Specifically, it
warns if the same actual argument is associated with a dummy
argument with `INTENT(IN)' and a dummy argument with `INTENT(OUT)'
in a call with an explicit interface.
The following example will trigger the warning.
interface
subroutine bar(a,b)
integer, intent(in) :: a
integer, intent(out) :: b
end subroutine
end interface
integer :: a
call bar(a,a)
`-Wampersand'
Warn about missing ampersand in continued character constants. The
warning is given with `-Wampersand', `-pedantic', `-std=f95',
`-std=f2003', `-std=f2008' and `-std=f2018'. Note: With no
ampersand given in a continued character constant, GNU Fortran
assumes continuation at the first non-comment, non-whitespace
character after the ampersand that initiated the continuation.
`-Wargument-mismatch'
Warn about type, rank, and other mismatches between formal
parameters and actual arguments to functions and subroutines.
These warnings are recommended and thus enabled by default.
`-Warray-temporaries'
Warn about array temporaries generated by the compiler. The
information generated by this warning is sometimes useful in
optimization, in order to avoid such temporaries.
`-Wc-binding-type'
Warn if the a variable might not be C interoperable. In
particular, warn if the variable has been declared using an
intrinsic type with default kind instead of using a kind parameter
defined for C interoperability in the intrinsic `ISO_C_Binding'
module. This option is implied by `-Wall'.
`-Wcharacter-truncation'
Warn when a character assignment will truncate the assigned string.
`-Wline-truncation'
Warn when a source code line will be truncated. This option is
implied by `-Wall'. For free-form source code, the default is
`-Werror=line-truncation' such that truncations are reported as
error.
`-Wconversion'
Warn about implicit conversions that are likely to change the
value of the expression after conversion. Implied by `-Wall'.
`-Wconversion-extra'
Warn about implicit conversions between different types and kinds.
This option does _not_ imply `-Wconversion'.
`-Wextra'
Enables some warning options for usages of language features which
may be problematic. This currently includes `-Wcompare-reals',
`-Wunused-parameter' and `-Wdo-subscript'.
`-Wfrontend-loop-interchange'
Enable warning for loop interchanges performed by the
`-ffrontend-loop-interchange' option.
`-Wimplicit-interface'
Warn if a procedure is called without an explicit interface. Note
this only checks that an explicit interface is present. It does
not check that the declared interfaces are consistent across
program units.
`-Wimplicit-procedure'
Warn if a procedure is called that has neither an explicit
interface nor has been declared as `EXTERNAL'.
`-Winteger-division'
Warn if a constant integer division truncates it result. As an
example, 3/5 evaluates to 0.
`-Wintrinsics-std'
Warn if `gfortran' finds a procedure named like an intrinsic not
available in the currently selected standard (with `-std') and
treats it as `EXTERNAL' procedure because of this.
`-fall-intrinsics' can be used to never trigger this behavior and
always link to the intrinsic regardless of the selected standard.
`-Wreal-q-constant'
Produce a warning if a real-literal-constant contains a `q'
exponent-letter.
`-Wsurprising'
Produce a warning when "suspicious" code constructs are
encountered. While technically legal these usually indicate that
an error has been made.
This currently produces a warning under the following
circumstances:
* An INTEGER SELECT construct has a CASE that can never be
matched as its lower value is greater than its upper value.
* A LOGICAL SELECT construct has three CASE statements.
* A TRANSFER specifies a source that is shorter than the
destination.
* The type of a function result is declared more than once with
the same type. If `-pedantic' or standard-conforming mode is
enabled, this is an error.
* A `CHARACTER' variable is declared with negative length.
`-Wtabs'
By default, tabs are accepted as whitespace, but tabs are not
members of the Fortran Character Set. For continuation lines, a
tab followed by a digit between 1 and 9 is supported. `-Wtabs'
will cause a warning to be issued if a tab is encountered. Note,
`-Wtabs' is active for `-pedantic', `-std=f95', `-std=f2003',
`-std=f2008', `-std=f2018' and `-Wall'.
`-Wundefined-do-loop'
Warn if a DO loop with step either 1 or -1 yields an underflow or
an overflow during iteration of an induction variable of the loop.
This option is implied by `-Wall'.
`-Wunderflow'
Produce a warning when numerical constant expressions are
encountered, which yield an UNDERFLOW during compilation. Enabled
by default.
`-Wintrinsic-shadow'
Warn if a user-defined procedure or module procedure has the same
name as an intrinsic; in this case, an explicit interface or
`EXTERNAL' or `INTRINSIC' declaration might be needed to get calls
later resolved to the desired intrinsic/procedure. This option is
implied by `-Wall'.
`-Wuse-without-only'
Warn if a `USE' statement has no `ONLY' qualifier and thus
implicitly imports all public entities of the used module.
`-Wunused-dummy-argument'
Warn about unused dummy arguments. This option is implied by
`-Wall'.
`-Wunused-parameter'
Contrary to `gcc''s meaning of `-Wunused-parameter', `gfortran''s
implementation of this option does not warn about unused dummy
arguments (see `-Wunused-dummy-argument'), but about unused
`PARAMETER' values. `-Wunused-parameter' is implied by `-Wextra'
if also `-Wunused' or `-Wall' is used.
`-Walign-commons'
By default, `gfortran' warns about any occasion of variables being
padded for proper alignment inside a `COMMON' block. This warning
can be turned off via `-Wno-align-commons'. See also
`-falign-commons'.
`-Wfunction-elimination'
Warn if any calls to impure functions are eliminated by the
optimizations enabled by the `-ffrontend-optimize' option. This
option is implied by `-Wextra'.
`-Wrealloc-lhs'
Warn when the compiler might insert code to for allocation or
reallocation of an allocatable array variable of intrinsic type in
intrinsic assignments. In hot loops, the Fortran 2003
reallocation feature may reduce the performance. If the array is
already allocated with the correct shape, consider using a
whole-array array-spec (e.g. `(:,:,:)') for the variable on the
left-hand side to prevent the reallocation check. Note that in
some cases the warning is shown, even if the compiler will
optimize reallocation checks away. For instance, when the
right-hand side contains the same variable multiplied by a scalar.
See also `-frealloc-lhs'.
`-Wrealloc-lhs-all'
Warn when the compiler inserts code to for allocation or
reallocation of an allocatable variable; this includes scalars and
derived types.
`-Wcompare-reals'
Warn when comparing real or complex types for equality or
inequality. This option is implied by `-Wextra'.
`-Wtarget-lifetime'
Warn if the pointer in a pointer assignment might be longer than
the its target. This option is implied by `-Wall'.
`-Wzerotrip'
Warn if a `DO' loop is known to execute zero times at compile
time. This option is implied by `-Wall'.
`-Wdo-subscript'
Warn if an array subscript inside a DO loop could lead to an
out-of-bounds access even if the compiler cannot prove that the
statement is actually executed, in cases like
real a(3)
do i=1,4
if (condition(i)) then
a(i) = 1.2
end if
end do
This option is implied by `-Wextra'.
`-Werror'
Turns all warnings into errors.
*Note Options to Request or Suppress Errors and Warnings:
(gcc)Warning Options, for information on more options offered by the
GBE shared by `gfortran', `gcc' and other GNU compilers.
Some of these have no effect when compiling programs written in
Fortran.

File: gfortran.info, Node: Debugging Options, Next: Directory Options, Prev: Error and Warning Options, Up: Invoking GNU Fortran
2.5 Options for debugging your program or GNU Fortran
=====================================================
GNU Fortran has various special options that are used for debugging
either your program or the GNU Fortran compiler.
`-fdump-fortran-original'
Output the internal parse tree after translating the source program
into internal representation. This option is mostly useful for
debugging the GNU Fortran compiler itself. The output generated by
this option might change between releases. This option may also
generate internal compiler errors for features which have only
recently been added.
`-fdump-fortran-optimized'
Output the parse tree after front-end optimization. Mostly useful
for debugging the GNU Fortran compiler itself. The output
generated by this option might change between releases. This
option may also generate internal compiler errors for features
which have only recently been added.
`-fdump-parse-tree'
Output the internal parse tree after translating the source program
into internal representation. Mostly useful for debugging the GNU
Fortran compiler itself. The output generated by this option might
change between releases. This option may also generate internal
compiler errors for features which have only recently been added.
This option is deprecated; use `-fdump-fortran-original' instead.
`-fdump-fortran-global'
Output a list of the global identifiers after translating into
middle-end representation. Mostly useful for debugging the GNU
Fortran compiler itself. The output generated by this option might
change between releases. This option may also generate internal
compiler errors for features which have only recently been added.
`-ffpe-trap=LIST'
Specify a list of floating point exception traps to enable. On
most systems, if a floating point exception occurs and the trap
for that exception is enabled, a SIGFPE signal will be sent and
the program being aborted, producing a core file useful for
debugging. LIST is a (possibly empty) comma-separated list of the
following exceptions: `invalid' (invalid floating point operation,
such as `SQRT(-1.0)'), `zero' (division by zero), `overflow'
(overflow in a floating point operation), `underflow' (underflow
in a floating point operation), `inexact' (loss of precision
during operation), and `denormal' (operation performed on a
denormal value). The first five exceptions correspond to the five
IEEE 754 exceptions, whereas the last one (`denormal') is not part
of the IEEE 754 standard but is available on some common
architectures such as x86.
The first three exceptions (`invalid', `zero', and `overflow')
often indicate serious errors, and unless the program has
provisions for dealing with these exceptions, enabling traps for
these three exceptions is probably a good idea.
If the option is used more than once in the command line, the
lists will be joined: '`ffpe-trap='LIST1 `ffpe-trap='LIST2' is
equivalent to `ffpe-trap='LIST1,LIST2.
Note that once enabled an exception cannot be disabled (no
negative form).
Many, if not most, floating point operations incur loss of
precision due to rounding, and hence the `ffpe-trap=inexact' is
likely to be uninteresting in practice.
By default no exception traps are enabled.
`-ffpe-summary=LIST'
Specify a list of floating-point exceptions, whose flag status is
printed to `ERROR_UNIT' when invoking `STOP' and `ERROR STOP'.
LIST can be either `none', `all' or a comma-separated list of the
following exceptions: `invalid', `zero', `overflow', `underflow',
`inexact' and `denormal'. (See `-ffpe-trap' for a description of
the exceptions.)
If the option is used more than once in the command line, only the
last one will be used.
By default, a summary for all exceptions but `inexact' is shown.
`-fno-backtrace'
When a serious runtime error is encountered or a deadly signal is
emitted (segmentation fault, illegal instruction, bus error,
floating-point exception, and the other POSIX signals that have the
action `core'), the Fortran runtime library tries to output a
backtrace of the error. `-fno-backtrace' disables the backtrace
generation. This option only has influence for compilation of the
Fortran main program.
*Note Options for Debugging Your Program or GCC: (gcc)Debugging
Options, for more information on debugging options.

File: gfortran.info, Node: Directory Options, Next: Link Options, Prev: Debugging Options, Up: Invoking GNU Fortran
2.6 Options for directory search
================================
These options affect how GNU Fortran searches for files specified by
the `INCLUDE' directive and where it searches for previously compiled
modules.
It also affects the search paths used by `cpp' when used to
preprocess Fortran source.
`-IDIR'
These affect interpretation of the `INCLUDE' directive (as well as
of the `#include' directive of the `cpp' preprocessor).
Also note that the general behavior of `-I' and `INCLUDE' is
pretty much the same as of `-I' with `#include' in the `cpp'
preprocessor, with regard to looking for `header.gcc' files and
other such things.
This path is also used to search for `.mod' files when previously
compiled modules are required by a `USE' statement.
*Note Options for Directory Search: (gcc)Directory Options, for
information on the `-I' option.
`-JDIR'
This option specifies where to put `.mod' files for compiled
modules. It is also added to the list of directories to searched
by an `USE' statement.
The default is the current directory.
`-fintrinsic-modules-path DIR'
This option specifies the location of pre-compiled intrinsic
modules, if they are not in the default location expected by the
compiler.

File: gfortran.info, Node: Link Options, Next: Runtime Options, Prev: Directory Options, Up: Invoking GNU Fortran
2.7 Influencing the linking step
================================
These options come into play when the compiler links object files into
an executable output file. They are meaningless if the compiler is not
doing a link step.
`-static-libgfortran'
On systems that provide `libgfortran' as a shared and a static
library, this option forces the use of the static version. If no
shared version of `libgfortran' was built when the compiler was
configured, this option has no effect.

File: gfortran.info, Node: Runtime Options, Next: Code Gen Options, Prev: Link Options, Up: Invoking GNU Fortran
2.8 Influencing runtime behavior
================================
These options affect the runtime behavior of programs compiled with GNU
Fortran.
`-fconvert=CONVERSION'
Specify the representation of data for unformatted files. Valid
values for conversion are: `native', the default; `swap', swap
between big- and little-endian; `big-endian', use big-endian
representation for unformatted files; `little-endian', use
little-endian representation for unformatted files.
_This option has an effect only when used in the main program.
The `CONVERT' specifier and the GFORTRAN_CONVERT_UNIT environment
variable override the default specified by `-fconvert'._
`-frecord-marker=LENGTH'
Specify the length of record markers for unformatted files. Valid
values for LENGTH are 4 and 8. Default is 4. _This is different
from previous versions of `gfortran'_, which specified a default
record marker length of 8 on most systems. If you want to read or
write files compatible with earlier versions of `gfortran', use
`-frecord-marker=8'.
`-fmax-subrecord-length=LENGTH'
Specify the maximum length for a subrecord. The maximum permitted
value for length is 2147483639, which is also the default. Only
really useful for use by the gfortran testsuite.
`-fsign-zero'
When enabled, floating point numbers of value zero with the sign
bit set are written as negative number in formatted output and
treated as negative in the `SIGN' intrinsic. `-fno-sign-zero'
does not print the negative sign of zero values (or values rounded
to zero for I/O) and regards zero as positive number in the `SIGN'
intrinsic for compatibility with Fortran 77. The default is
`-fsign-zero'.

File: gfortran.info, Node: Code Gen Options, Next: Interoperability Options, Prev: Runtime Options, Up: Invoking GNU Fortran
2.9 Options for code generation conventions
===========================================
These machine-independent options control the interface conventions
used in code generation.
Most of them have both positive and negative forms; the negative form
of `-ffoo' would be `-fno-foo'. In the table below, only one of the
forms is listed--the one which is not the default. You can figure out
the other form by either removing `no-' or adding it.
`-fno-automatic'
Treat each program unit (except those marked as RECURSIVE) as if
the `SAVE' statement were specified for every local variable and
array referenced in it. Does not affect common blocks. (Some
Fortran compilers provide this option under the name `-static' or
`-save'.) The default, which is `-fautomatic', uses the stack for
local variables smaller than the value given by
`-fmax-stack-var-size'. Use the option `-frecursive' to use no
static memory.
Local variables or arrays having an explicit `SAVE' attribute are
silently ignored unless the `-pedantic' option is added.
`-ff2c'
Generate code designed to be compatible with code generated by
`g77' and `f2c'.
The calling conventions used by `g77' (originally implemented in
`f2c') require functions that return type default `REAL' to
actually return the C type `double', and functions that return
type `COMPLEX' to return the values via an extra argument in the
calling sequence that points to where to store the return value.
Under the default GNU calling conventions, such functions simply
return their results as they would in GNU C--default `REAL'
functions return the C type `float', and `COMPLEX' functions
return the GNU C type `complex'. Additionally, this option
implies the `-fsecond-underscore' option, unless
`-fno-second-underscore' is explicitly requested.
This does not affect the generation of code that interfaces with
the `libgfortran' library.
_Caution:_ It is not a good idea to mix Fortran code compiled with
`-ff2c' with code compiled with the default `-fno-f2c' calling
conventions as, calling `COMPLEX' or default `REAL' functions
between program parts which were compiled with different calling
conventions will break at execution time.
_Caution:_ This will break code which passes intrinsic functions
of type default `REAL' or `COMPLEX' as actual arguments, as the
library implementations use the `-fno-f2c' calling conventions.
`-fno-underscoring'
Do not transform names of entities specified in the Fortran source
file by appending underscores to them.
With `-funderscoring' in effect, GNU Fortran appends one
underscore to external names with no underscores. This is done to
ensure compatibility with code produced by many UNIX Fortran
compilers.
_Caution_: The default behavior of GNU Fortran is incompatible
with `f2c' and `g77', please use the `-ff2c' option if you want
object files compiled with GNU Fortran to be compatible with
object code created with these tools.
Use of `-fno-underscoring' is not recommended unless you are
experimenting with issues such as integration of GNU Fortran into
existing system environments (vis-a`-vis existing libraries, tools,
and so on).
For example, with `-funderscoring', and assuming that `j()' and
`max_count()' are external functions while `my_var' and `lvar' are
local variables, a statement like
I = J() + MAX_COUNT (MY_VAR, LVAR)
is implemented as something akin to:
i = j_() + max_count__(&my_var__, &lvar);
With `-fno-underscoring', the same statement is implemented as:
i = j() + max_count(&my_var, &lvar);
Use of `-fno-underscoring' allows direct specification of
user-defined names while debugging and when interfacing GNU Fortran
code with other languages.
Note that just because the names match does _not_ mean that the
interface implemented by GNU Fortran for an external name matches
the interface implemented by some other language for that same
name. That is, getting code produced by GNU Fortran to link to
code produced by some other compiler using this or any other
method can be only a small part of the overall solution--getting
the code generated by both compilers to agree on issues other than
naming can require significant effort, and, unlike naming
disagreements, linkers normally cannot detect disagreements in
these other areas.
Also, note that with `-fno-underscoring', the lack of appended
underscores introduces the very real possibility that a
user-defined external name will conflict with a name in a system
library, which could make finding unresolved-reference bugs quite
difficult in some cases--they might occur at program run time, and
show up only as buggy behavior at run time.
In future versions of GNU Fortran we hope to improve naming and
linking issues so that debugging always involves using the names
as they appear in the source, even if the names as seen by the
linker are mangled to prevent accidental linking between
procedures with incompatible interfaces.
`-fsecond-underscore'
By default, GNU Fortran appends an underscore to external names.
If this option is used GNU Fortran appends two underscores to
names with underscores and one underscore to external names with
no underscores. GNU Fortran also appends two underscores to
internal names with underscores to avoid naming collisions with
external names.
This option has no effect if `-fno-underscoring' is in effect. It
is implied by the `-ff2c' option.
Otherwise, with this option, an external name such as `MAX_COUNT'
is implemented as a reference to the link-time external symbol
`max_count__', instead of `max_count_'. This is required for
compatibility with `g77' and `f2c', and is implied by use of the
`-ff2c' option.
`-fcoarray=<KEYWORD>'
`none'
Disable coarray support; using coarray declarations and
image-control statements will produce a compile-time error.
(Default)
`single'
Single-image mode, i.e. `num_images()' is always one.
`lib'
Library-based coarray parallelization; a suitable GNU Fortran
coarray library needs to be linked.
`-fcheck=<KEYWORD>'
Enable the generation of run-time checks; the argument shall be a
comma-delimited list of the following keywords. Prefixing a check
with `no-' disables it if it was activated by a previous
specification.
`all'
Enable all run-time test of `-fcheck'.
`array-temps'
Warns at run time when for passing an actual argument a
temporary array had to be generated. The information
generated by this warning is sometimes useful in
optimization, in order to avoid such temporaries.
Note: The warning is only printed once per location.
`bounds'
Enable generation of run-time checks for array subscripts and
against the declared minimum and maximum values. It also
checks array indices for assumed and deferred shape arrays
against the actual allocated bounds and ensures that all
string lengths are equal for character array constructors
without an explicit typespec.
Some checks require that `-fcheck=bounds' is set for the
compilation of the main program.
Note: In the future this may also include other forms of
checking, e.g., checking substring references.
`do'
Enable generation of run-time checks for invalid modification
of loop iteration variables.
`mem'
Enable generation of run-time checks for memory allocation.
Note: This option does not affect explicit allocations using
the `ALLOCATE' statement, which will be always checked.
`pointer'
Enable generation of run-time checks for pointers and
allocatables.
`recursion'
Enable generation of run-time checks for recursively called
subroutines and functions which are not marked as recursive.
See also `-frecursive'. Note: This check does not work for
OpenMP programs and is disabled if used together with
`-frecursive' and `-fopenmp'.
Example: Assuming you have a file `foo.f90', the command
gfortran -fcheck=all,no-array-temps foo.f90
will compile the file with all checks enabled as specified above
except warnings for generated array temporaries.
`-fbounds-check'
Deprecated alias for `-fcheck=bounds'.
`-ftail-call-workaround'
`-ftail-call-workaround=N'
Some C interfaces to Fortran codes violate the gfortran ABI by
omitting the hidden character length arguments as described in
*Note Argument passing conventions::. This can lead to crashes
because pushing arguments for tail calls can overflow the stack.
To provide a workaround for existing binary packages, this option
disables tail call optimization for gfortran procedures with
character arguments. With `-ftail-call-workaround=2' tail call
optimization is disabled in all gfortran procedures with character
arguments, with `-ftail-call-workaround=1' or equivalent
`-ftail-call-workaround' only in gfortran procedures with character
arguments that call implicitly prototyped procedures.
Using this option can lead to problems including crashes due to
insufficient stack space.
It is _very strongly_ recommended to fix the code in question.
The `-fc-prototypes-external' option can be used to generate
prototypes which conform to gfortran's ABI, for inclusion in the
source code.
Support for this option will likely be withdrawn in a future
release of gfortran.
The negative form, `-fno-tail-call-workaround' or equivalent
`-ftail-call-workaround=0', can be used to disable this option.
Default is currently `-ftail-call-workaround', this will change in
future releases.
`-fcheck-array-temporaries'
Deprecated alias for `-fcheck=array-temps'.
`-fmax-array-constructor=N'
This option can be used to increase the upper limit permitted in
array constructors. The code below requires this option to expand
the array at compile time.
program test
implicit none
integer j
integer, parameter :: n = 100000
integer, parameter :: i(n) = (/ (2*j, j = 1, n) /)
print '(10(I0,1X))', i
end program test
_Caution: This option can lead to long compile times and
excessively large object files._
The default value for N is 65535.
`-fmax-stack-var-size=N'
This option specifies the size in bytes of the largest array that
will be put on the stack; if the size is exceeded static memory is
used (except in procedures marked as RECURSIVE). Use the option
`-frecursive' to allow for recursive procedures which do not have
a RECURSIVE attribute or for parallel programs. Use
`-fno-automatic' to never use the stack.
This option currently only affects local arrays declared with
constant bounds, and may not apply to all character variables.
Future versions of GNU Fortran may improve this behavior.
The default value for N is 32768.
`-fstack-arrays'
Adding this option will make the Fortran compiler put all arrays of
unknown size and array temporaries onto stack memory. If your
program uses very large local arrays it is possible that you will
have to extend your runtime limits for stack memory on some
operating systems. This flag is enabled by default at optimization
level `-Ofast' unless `-fmax-stack-var-size' is specified.
`-fpack-derived'
This option tells GNU Fortran to pack derived type members as
closely as possible. Code compiled with this option is likely to
be incompatible with code compiled without this option, and may
execute slower.
`-frepack-arrays'
In some circumstances GNU Fortran may pass assumed shape array
sections via a descriptor describing a noncontiguous area of
memory. This option adds code to the function prologue to repack
the data into a contiguous block at runtime.
This should result in faster accesses to the array. However it
can introduce significant overhead to the function call,
especially when the passed data is noncontiguous.
`-fshort-enums'
This option is provided for interoperability with C code that was
compiled with the `-fshort-enums' option. It will make GNU
Fortran choose the smallest `INTEGER' kind a given enumerator set
will fit in, and give all its enumerators this kind.
`-fexternal-blas'
This option will make `gfortran' generate calls to BLAS functions
for some matrix operations like `MATMUL', instead of using our own
algorithms, if the size of the matrices involved is larger than a
given limit (see `-fblas-matmul-limit'). This may be profitable
if an optimized vendor BLAS library is available. The BLAS
library will have to be specified at link time.
`-fblas-matmul-limit=N'
Only significant when `-fexternal-blas' is in effect. Matrix
multiplication of matrices with size larger than (or equal to) N
will be performed by calls to BLAS functions, while others will be
handled by `gfortran' internal algorithms. If the matrices
involved are not square, the size comparison is performed using the
geometric mean of the dimensions of the argument and result
matrices.
The default value for N is 30.
`-finline-matmul-limit=N'
When front-end optimiztion is active, some calls to the `MATMUL'
intrinsic function will be inlined. This may result in code size
increase if the size of the matrix cannot be determined at compile
time, as code for both cases is generated. Setting
`-finline-matmul-limit=0' will disable inlining in all cases.
Setting this option with a value of N will produce inline code for
matrices with size up to N. If the matrices involved are not
square, the size comparison is performed using the geometric mean
of the dimensions of the argument and result matrices.
The default value for N is 30. The `-fblas-matmul-limit' can be
used to change this value.
`-frecursive'
Allow indirect recursion by forcing all local arrays to be
allocated on the stack. This flag cannot be used together with
`-fmax-stack-var-size=' or `-fno-automatic'.
`-finit-local-zero'
`-finit-derived'
`-finit-integer=N'
`-finit-real=<ZERO|INF|-INF|NAN|SNAN>'
`-finit-logical=<TRUE|FALSE>'
`-finit-character=N'
The `-finit-local-zero' option instructs the compiler to
initialize local `INTEGER', `REAL', and `COMPLEX' variables to
zero, `LOGICAL' variables to false, and `CHARACTER' variables to a
string of null bytes. Finer-grained initialization options are
provided by the `-finit-integer=N',
`-finit-real=<ZERO|INF|-INF|NAN|SNAN>' (which also initializes the
real and imaginary parts of local `COMPLEX' variables),
`-finit-logical=<TRUE|FALSE>', and `-finit-character=N' (where N
is an ASCII character value) options.
With `-finit-derived', components of derived type variables will be
initialized according to these flags. Components whose type is
not covered by an explicit `-finit-*' flag will be treated as
described above with `-finit-local-zero'.
These options do not initialize
* objects with the POINTER attribute
* allocatable arrays
* variables that appear in an `EQUIVALENCE' statement.
(These limitations may be removed in future releases).
Note that the `-finit-real=nan' option initializes `REAL' and
`COMPLEX' variables with a quiet NaN. For a signalling NaN use
`-finit-real=snan'; note, however, that compile-time optimizations
may convert them into quiet NaN and that trapping needs to be
enabled (e.g. via `-ffpe-trap').
The `-finit-integer' option will parse the value into an integer
of type `INTEGER(kind=C_LONG)' on the host. Said value is then
assigned to the integer variables in the Fortran code, which might
result in wraparound if the value is too large for the kind.
Finally, note that enabling any of the `-finit-*' options will
silence warnings that would have been emitted by `-Wuninitialized'
for the affected local variables.
`-falign-commons'
By default, `gfortran' enforces proper alignment of all variables
in a `COMMON' block by padding them as needed. On certain
platforms this is mandatory, on others it increases performance.
If a `COMMON' block is not declared with consistent data types
everywhere, this padding can cause trouble, and
`-fno-align-commons' can be used to disable automatic alignment.
The same form of this option should be used for all files that
share a `COMMON' block. To avoid potential alignment issues in
`COMMON' blocks, it is recommended to order objects from largest
to smallest.
`-fno-protect-parens'
By default the parentheses in expression are honored for all
optimization levels such that the compiler does not do any
re-association. Using `-fno-protect-parens' allows the compiler to
reorder `REAL' and `COMPLEX' expressions to produce faster code.
Note that for the re-association optimization `-fno-signed-zeros'
and `-fno-trapping-math' need to be in effect. The parentheses
protection is enabled by default, unless `-Ofast' is given.
`-frealloc-lhs'
An allocatable left-hand side of an intrinsic assignment is
automatically (re)allocated if it is either unallocated or has a
different shape. The option is enabled by default except when
`-std=f95' is given. See also `-Wrealloc-lhs'.
`-faggressive-function-elimination'
Functions with identical argument lists are eliminated within
statements, regardless of whether these functions are marked
`PURE' or not. For example, in
a = f(b,c) + f(b,c)
there will only be a single call to `f'. This option only works
if `-ffrontend-optimize' is in effect.
`-ffrontend-optimize'
This option performs front-end optimization, based on manipulating
parts the Fortran parse tree. Enabled by default by any `-O'
option except `-O0' and `-Og'. Optimizations enabled by this
option include:
* inlining calls to `MATMUL',
* elimination of identical function calls within expressions,
* removing unnecessary calls to `TRIM' in comparisons and
assignments,
* replacing `TRIM(a)' with `a(1:LEN_TRIM(a))' and
* short-circuiting of logical operators (`.AND.' and `.OR.').
It can be deselected by specifying `-fno-frontend-optimize'.
`-ffrontend-loop-interchange'
Attempt to interchange loops in the Fortran front end where
profitable. Enabled by default by any `-O' option. At the
moment, this option only affects `FORALL' and `DO CONCURRENT'
statements with several forall triplets.
*Note Options for Code Generation Conventions: (gcc)Code Gen
Options, for information on more options offered by the GBE shared by
`gfortran', `gcc', and other GNU compilers.

File: gfortran.info, Node: Interoperability Options, Next: Environment Variables, Prev: Code Gen Options, Up: Invoking GNU Fortran
2.10 Options for interoperability with other languages
======================================================
-fc-prototypes
This option will generate C prototypes from `BIND(C)' variable
declarations, types and procedure interfaces and writes them to
standard output. `ENUM' is not yet supported.
The generated prototypes may need inclusion of an appropriate
header, such as `<stdint.h>' or `<stdlib.h>'. For types which are
not specified using the appropriate kind from the `iso_c_binding'
module, a warning is added as a comment to the code.
For function pointers, a pointer to a function returning `int'
without an explicit argument list is generated.
Example of use:
$ gfortran -fc-prototypes -fsyntax-only foo.f90 > foo.h
where the C code intended for interoperating with the Fortran code
then uses `#include "foo.h"'.
-fc-prototypes-external
This option will generate C prototypes from external functions and
subroutines and write them to standard output. This may be useful
for making sure that C bindings to Fortran code are correct. This
option does not generate prototypes for `BIND(C)' procedures, use
`-fc-prototypes' for that.
The generated prototypes may need inclusion of an appropriate
header, such as as `<stdint.h>' or `<stdlib.h>'.
This is primarily meant for legacy code to ensure that existing C
bindings match what `gfortran' emits. The generated C prototypes
should be correct for the current version of the compiler, but may
not match what other compilers or earlier versions of `gfortran'
need. For new developments, use of the `BIND(C)' features is
recommended.
Example of use:
$ gfortran -fc-prototypes-external -fsyntax-only foo.f > foo.h
where the C code intended for interoperating with the Fortran code
then uses `#include "foo.h"'.

File: gfortran.info, Node: Environment Variables, Prev: Interoperability Options, Up: Invoking GNU Fortran
2.11 Environment variables affecting `gfortran'
===============================================
The `gfortran' compiler currently does not make use of any environment
variables to control its operation above and beyond those that affect
the operation of `gcc'.
*Note Environment Variables Affecting GCC: (gcc)Environment
Variables, for information on environment variables.
*Note Runtime::, for environment variables that affect the run-time
behavior of programs compiled with GNU Fortran.

File: gfortran.info, Node: Runtime, Next: Fortran standards status, Prev: Invoking GNU Fortran, Up: Top
3 Runtime: Influencing runtime behavior with environment variables
*******************************************************************
The behavior of the `gfortran' can be influenced by environment
variables.
Malformed environment variables are silently ignored.
* Menu:
* TMPDIR:: Directory for scratch files
* GFORTRAN_STDIN_UNIT:: Unit number for standard input
* GFORTRAN_STDOUT_UNIT:: Unit number for standard output
* GFORTRAN_STDERR_UNIT:: Unit number for standard error
* GFORTRAN_UNBUFFERED_ALL:: Do not buffer I/O for all units.
* GFORTRAN_UNBUFFERED_PRECONNECTED:: Do not buffer I/O for preconnected units.
* GFORTRAN_SHOW_LOCUS:: Show location for runtime errors
* GFORTRAN_OPTIONAL_PLUS:: Print leading + where permitted
* GFORTRAN_LIST_SEPARATOR:: Separator for list output
* GFORTRAN_CONVERT_UNIT:: Set endianness for unformatted I/O
* GFORTRAN_ERROR_BACKTRACE:: Show backtrace on run-time errors
* GFORTRAN_FORMATTED_BUFFER_SIZE:: Buffer size for formatted files.
* GFORTRAN_UNFORMATTED_BUFFER_SIZE:: Buffer size for unformatted files.

File: gfortran.info, Node: TMPDIR, Next: GFORTRAN_STDIN_UNIT, Up: Runtime
3.1 `TMPDIR'--Directory for scratch files
=========================================
When opening a file with `STATUS='SCRATCH'', GNU Fortran tries to
create the file in one of the potential directories by testing each
directory in the order below.
1. The environment variable `TMPDIR', if it exists.
2. On the MinGW target, the directory returned by the `GetTempPath'
function. Alternatively, on the Cygwin target, the `TMP' and
`TEMP' environment variables, if they exist, in that order.
3. The `P_tmpdir' macro if it is defined, otherwise the directory
`/tmp'.

File: gfortran.info, Node: GFORTRAN_STDIN_UNIT, Next: GFORTRAN_STDOUT_UNIT, Prev: TMPDIR, Up: Runtime
3.2 `GFORTRAN_STDIN_UNIT'--Unit number for standard input
=========================================================
This environment variable can be used to select the unit number
preconnected to standard input. This must be a positive integer. The
default value is 5.

File: gfortran.info, Node: GFORTRAN_STDOUT_UNIT, Next: GFORTRAN_STDERR_UNIT, Prev: GFORTRAN_STDIN_UNIT, Up: Runtime
3.3 `GFORTRAN_STDOUT_UNIT'--Unit number for standard output
===========================================================
This environment variable can be used to select the unit number
preconnected to standard output. This must be a positive integer. The
default value is 6.

File: gfortran.info, Node: GFORTRAN_STDERR_UNIT, Next: GFORTRAN_UNBUFFERED_ALL, Prev: GFORTRAN_STDOUT_UNIT, Up: Runtime
3.4 `GFORTRAN_STDERR_UNIT'--Unit number for standard error
==========================================================
This environment variable can be used to select the unit number
preconnected to standard error. This must be a positive integer. The
default value is 0.

File: gfortran.info, Node: GFORTRAN_UNBUFFERED_ALL, Next: GFORTRAN_UNBUFFERED_PRECONNECTED, Prev: GFORTRAN_STDERR_UNIT, Up: Runtime
3.5 `GFORTRAN_UNBUFFERED_ALL'--Do not buffer I/O on all units
=============================================================
This environment variable controls whether all I/O is unbuffered. If
the first letter is `y', `Y' or `1', all I/O is unbuffered. This will
slow down small sequential reads and writes. If the first letter is
`n', `N' or `0', I/O is buffered. This is the default.

File: gfortran.info, Node: GFORTRAN_UNBUFFERED_PRECONNECTED, Next: GFORTRAN_SHOW_LOCUS, Prev: GFORTRAN_UNBUFFERED_ALL, Up: Runtime
3.6 `GFORTRAN_UNBUFFERED_PRECONNECTED'--Do not buffer I/O on preconnected units
===============================================================================
The environment variable named `GFORTRAN_UNBUFFERED_PRECONNECTED'
controls whether I/O on a preconnected unit (i.e. STDOUT or STDERR) is
unbuffered. If the first letter is `y', `Y' or `1', I/O is unbuffered.
This will slow down small sequential reads and writes. If the first
letter is `n', `N' or `0', I/O is buffered. This is the default.

File: gfortran.info, Node: GFORTRAN_SHOW_LOCUS, Next: GFORTRAN_OPTIONAL_PLUS, Prev: GFORTRAN_UNBUFFERED_PRECONNECTED, Up: Runtime
3.7 `GFORTRAN_SHOW_LOCUS'--Show location for runtime errors
===========================================================
If the first letter is `y', `Y' or `1', filename and line numbers for
runtime errors are printed. If the first letter is `n', `N' or `0', do
not print filename and line numbers for runtime errors. The default is
to print the location.

File: gfortran.info, Node: GFORTRAN_OPTIONAL_PLUS, Next: GFORTRAN_LIST_SEPARATOR, Prev: GFORTRAN_SHOW_LOCUS, Up: Runtime
3.8 `GFORTRAN_OPTIONAL_PLUS'--Print leading + where permitted
=============================================================
If the first letter is `y', `Y' or `1', a plus sign is printed where
permitted by the Fortran standard. If the first letter is `n', `N' or
`0', a plus sign is not printed in most cases. Default is not to print
plus signs.

File: gfortran.info, Node: GFORTRAN_LIST_SEPARATOR, Next: GFORTRAN_CONVERT_UNIT, Prev: GFORTRAN_OPTIONAL_PLUS, Up: Runtime
3.9 `GFORTRAN_LIST_SEPARATOR'--Separator for list output
========================================================
This environment variable specifies the separator when writing
list-directed output. It may contain any number of spaces and at most
one comma. If you specify this on the command line, be sure to quote
spaces, as in
$ GFORTRAN_LIST_SEPARATOR=' , ' ./a.out
when `a.out' is the compiled Fortran program that you want to run.
Default is a single space.

File: gfortran.info, Node: GFORTRAN_CONVERT_UNIT, Next: GFORTRAN_ERROR_BACKTRACE, Prev: GFORTRAN_LIST_SEPARATOR, Up: Runtime
3.10 `GFORTRAN_CONVERT_UNIT'--Set endianness for unformatted I/O
================================================================
By setting the `GFORTRAN_CONVERT_UNIT' variable, it is possible to
change the representation of data for unformatted files. The syntax
for the `GFORTRAN_CONVERT_UNIT' variable is:
GFORTRAN_CONVERT_UNIT: mode | mode ';' exception | exception ;
mode: 'native' | 'swap' | 'big_endian' | 'little_endian' ;
exception: mode ':' unit_list | unit_list ;
unit_list: unit_spec | unit_list unit_spec ;
unit_spec: INTEGER | INTEGER '-' INTEGER ;
The variable consists of an optional default mode, followed by a
list of optional exceptions, which are separated by semicolons from the
preceding default and each other. Each exception consists of a format
and a comma-separated list of units. Valid values for the modes are
the same as for the `CONVERT' specifier:
`NATIVE' Use the native format. This is the default.
`SWAP' Swap between little- and big-endian.
`LITTLE_ENDIAN' Use the little-endian format for unformatted files.
`BIG_ENDIAN' Use the big-endian format for unformatted files.
A missing mode for an exception is taken to mean `BIG_ENDIAN'.
Examples of values for `GFORTRAN_CONVERT_UNIT' are:
`'big_endian'' Do all unformatted I/O in big_endian mode.
`'little_endian;native:10-20,25'' Do all unformatted I/O in
little_endian mode, except for units 10 to 20 and 25, which are in
native format.
`'10-20'' Units 10 to 20 are big-endian, the rest is native.
Setting the environment variables should be done on the command line
or via the `export' command for `sh'-compatible shells and via `setenv'
for `csh'-compatible shells.
Example for `sh':
$ gfortran foo.f90
$ GFORTRAN_CONVERT_UNIT='big_endian;native:10-20' ./a.out
Example code for `csh':
% gfortran foo.f90
% setenv GFORTRAN_CONVERT_UNIT 'big_endian;native:10-20'
% ./a.out
Using anything but the native representation for unformatted data
carries a significant speed overhead. If speed in this area matters to
you, it is best if you use this only for data that needs to be portable.
*Note CONVERT specifier::, for an alternative way to specify the
data representation for unformatted files. *Note Runtime Options::, for
setting a default data representation for the whole program. The
`CONVERT' specifier overrides the `-fconvert' compile options.
_Note that the values specified via the GFORTRAN_CONVERT_UNIT
environment variable will override the CONVERT specifier in the open
statement_. This is to give control over data formats to users who do
not have the source code of their program available.

File: gfortran.info, Node: GFORTRAN_ERROR_BACKTRACE, Next: GFORTRAN_FORMATTED_BUFFER_SIZE, Prev: GFORTRAN_CONVERT_UNIT, Up: Runtime
3.11 `GFORTRAN_ERROR_BACKTRACE'--Show backtrace on run-time errors
==================================================================
If the `GFORTRAN_ERROR_BACKTRACE' variable is set to `y', `Y' or `1'
(only the first letter is relevant) then a backtrace is printed when a
serious run-time error occurs. To disable the backtracing, set the
variable to `n', `N', `0'. Default is to print a backtrace unless the
`-fno-backtrace' compile option was used.

File: gfortran.info, Node: GFORTRAN_FORMATTED_BUFFER_SIZE, Next: GFORTRAN_UNFORMATTED_BUFFER_SIZE, Prev: GFORTRAN_ERROR_BACKTRACE, Up: Runtime
3.12 `GFORTRAN_FORMATTED_BUFFER_SIZE'--Set buffer size for formatted I/O
========================================================================
The `GFORTRAN_FORMATTED_BUFFER_SIZE' environment variable specifies
buffer size in bytes to be used for formatted output. The default
value is 8192.

File: gfortran.info, Node: GFORTRAN_UNFORMATTED_BUFFER_SIZE, Prev: GFORTRAN_FORMATTED_BUFFER_SIZE, Up: Runtime
3.13 `GFORTRAN_UNFORMATTED_BUFFER_SIZE'--Set buffer size for unformatted I/O
============================================================================
The `GFORTRAN_UNFORMATTED_BUFFER_SIZE' environment variable specifies
buffer size in bytes to be used for unformatted output. The default
value is 131072.

File: gfortran.info, Node: Fortran standards status, Next: Compiler Characteristics, Prev: Runtime, Up: Top
4 Fortran standards status
**************************
* Menu:
* Fortran 2003 status::
* Fortran 2008 status::
* Fortran 2018 status::

File: gfortran.info, Node: Fortran 2003 status, Next: Fortran 2008 status, Up: Fortran standards status
4.1 Fortran 2003 status
=======================
GNU Fortran supports several Fortran 2003 features; an incomplete list
can be found below. See also the wiki page
(https://gcc.gnu.org/wiki/Fortran2003) about Fortran 2003.
* Procedure pointers including procedure-pointer components with
`PASS' attribute.
* Procedures which are bound to a derived type (type-bound
procedures) including `PASS', `PROCEDURE' and `GENERIC', and
operators bound to a type.
* Abstract interfaces and type extension with the possibility to
override type-bound procedures or to have deferred binding.
* Polymorphic entities ("`CLASS'") for derived types and unlimited
polymorphism ("`CLASS(*)'") - including `SAME_TYPE_AS',
`EXTENDS_TYPE_OF' and `SELECT TYPE' for scalars and arrays and
finalization.
* Generic interface names, which have the same name as derived types,
are now supported. This allows one to write constructor functions.
Note that Fortran does not support static constructor functions.
For static variables, only default initialization or
structure-constructor initialization are available.
* The `ASSOCIATE' construct.
* Interoperability with C including enumerations,
* In structure constructors the components with default values may be
omitted.
* Extensions to the `ALLOCATE' statement, allowing for a
type-specification with type parameter and for allocation and
initialization from a `SOURCE=' expression; `ALLOCATE' and
`DEALLOCATE' optionally return an error message string via
`ERRMSG='.
* Reallocation on assignment: If an intrinsic assignment is used, an
allocatable variable on the left-hand side is automatically
allocated (if unallocated) or reallocated (if the shape is
different). Currently, scalar deferred character length left-hand
sides are correctly handled but arrays are not yet fully
implemented.
* Deferred-length character variables and scalar deferred-length
character components of derived types are supported. (Note that
array-valued compoents are not yet implemented.)
* Transferring of allocations via `MOVE_ALLOC'.
* The `PRIVATE' and `PUBLIC' attributes may be given individually to
derived-type components.
* In pointer assignments, the lower bound may be specified and the
remapping of elements is supported.
* For pointers an `INTENT' may be specified which affect the
association status not the value of the pointer target.
* Intrinsics `command_argument_count', `get_command',
`get_command_argument', and `get_environment_variable'.
* Support for Unicode characters (ISO 10646) and UTF-8, including
the `SELECTED_CHAR_KIND' and `NEW_LINE' intrinsic functions.
* Support for binary, octal and hexadecimal (BOZ) constants in the
intrinsic functions `INT', `REAL', `CMPLX' and `DBLE'.
* Support for namelist variables with allocatable and pointer
attribute and nonconstant length type parameter.
* Array constructors using square brackets. That is, `[...]' rather
than `(/.../)'. Type-specification for array constructors like
`(/ some-type :: ... /)'.
* Extensions to the specification and initialization expressions,
including the support for intrinsics with real and complex
arguments.
* Support for the asynchronous input/output.
* `FLUSH' statement.
* `IOMSG=' specifier for I/O statements.
* Support for the declaration of enumeration constants via the
`ENUM' and `ENUMERATOR' statements. Interoperability with `gcc'
is guaranteed also for the case where the `-fshort-enums' command
line option is given.
* TR 15581:
* `ALLOCATABLE' dummy arguments.
* `ALLOCATABLE' function results
* `ALLOCATABLE' components of derived types
* The `OPEN' statement supports the `ACCESS='STREAM'' specifier,
allowing I/O without any record structure.
* Namelist input/output for internal files.
* Minor I/O features: Rounding during formatted output, using of a
decimal comma instead of a decimal point, setting whether a plus
sign should appear for positive numbers. On systems where `strtod'
honours the rounding mode, the rounding mode is also supported for
input.
* The `PROTECTED' statement and attribute.
* The `VALUE' statement and attribute.
* The `VOLATILE' statement and attribute.
* The `IMPORT' statement, allowing to import host-associated derived
types.
* The intrinsic modules `ISO_FORTRAN_ENVIRONMENT' is supported,
which contains parameters of the I/O units, storage sizes.
Additionally, procedures for C interoperability are available in
the `ISO_C_BINDING' module.
* `USE' statement with `INTRINSIC' and `NON_INTRINSIC' attribute;
supported intrinsic modules: `ISO_FORTRAN_ENV', `ISO_C_BINDING',
`OMP_LIB' and `OMP_LIB_KINDS', and `OPENACC'.
* Renaming of operators in the `USE' statement.

File: gfortran.info, Node: Fortran 2008 status, Next: Fortran 2018 status, Prev: Fortran 2003 status, Up: Fortran standards status
4.2 Fortran 2008 status
=======================
The latest version of the Fortran standard is ISO/IEC 1539-1:2010,
informally known as Fortran 2008. The official version is available
from International Organization for Standardization (ISO) or its
national member organizations. The the final draft (FDIS) can be
downloaded free of charge from
`http://www.nag.co.uk/sc22wg5/links.html'. Fortran is developed by the
Working Group 5 of Sub-Committee 22 of the Joint Technical Committee 1
of the International Organization for Standardization and the
International Electrotechnical Commission (IEC). This group is known as
WG5 (http://www.nag.co.uk/sc22wg5/).
The GNU Fortran compiler supports several of the new features of
Fortran 2008; the wiki (https://gcc.gnu.org/wiki/Fortran2008Status) has
some information about the current Fortran 2008 implementation status.
In particular, the following is implemented.
* The `-std=f2008' option and support for the file extensions `.f08'
and `.F08'.
* The `OPEN' statement now supports the `NEWUNIT=' option, which
returns a unique file unit, thus preventing inadvertent use of the
same unit in different parts of the program.
* The `g0' format descriptor and unlimited format items.
* The mathematical intrinsics `ASINH', `ACOSH', `ATANH', `ERF',
`ERFC', `GAMMA', `LOG_GAMMA', `BESSEL_J0', `BESSEL_J1',
`BESSEL_JN', `BESSEL_Y0', `BESSEL_Y1', `BESSEL_YN', `HYPOT',
`NORM2', and `ERFC_SCALED'.
* Using complex arguments with `TAN', `SINH', `COSH', `TANH',
`ASIN', `ACOS', and `ATAN' is now possible; `ATAN'(Y,X) is now an
alias for `ATAN2'(Y,X).
* Support of the `PARITY' intrinsic functions.
* The following bit intrinsics: `LEADZ' and `TRAILZ' for counting
the number of leading and trailing zero bits, `POPCNT' and
`POPPAR' for counting the number of one bits and returning the
parity; `BGE', `BGT', `BLE', and `BLT' for bitwise comparisons;
`DSHIFTL' and `DSHIFTR' for combined left and right shifts,
`MASKL' and `MASKR' for simple left and right justified masks,
`MERGE_BITS' for a bitwise merge using a mask, `SHIFTA', `SHIFTL'
and `SHIFTR' for shift operations, and the transformational bit
intrinsics `IALL', `IANY' and `IPARITY'.
* Support of the `EXECUTE_COMMAND_LINE' intrinsic subroutine.
* Support for the `STORAGE_SIZE' intrinsic inquiry function.
* The `INT{8,16,32}' and `REAL{32,64,128}' kind type parameters and
the array-valued named constants `INTEGER_KINDS', `LOGICAL_KINDS',
`REAL_KINDS' and `CHARACTER_KINDS' of the intrinsic module
`ISO_FORTRAN_ENV'.
* The module procedures `C_SIZEOF' of the intrinsic module
`ISO_C_BINDINGS' and `COMPILER_VERSION' and `COMPILER_OPTIONS' of
`ISO_FORTRAN_ENV'.
* Coarray support for serial programs with `-fcoarray=single' flag
and experimental support for multiple images with the
`-fcoarray=lib' flag.
* Submodules are supported. It should noted that `MODULEs' do not
produce the smod file needed by the descendent `SUBMODULEs' unless
they contain at least one `MODULE PROCEDURE' interface. The reason
for this is that `SUBMODULEs' are useless without `MODULE
PROCEDUREs'. See http://j3-fortran.org/doc/meeting/207/15-209.txt
for a discussion and a draft interpretation. Adopting this
interpretation has the advantage that code that does not use
submodules does not generate smod files.
* The `DO CONCURRENT' construct is supported.
* The `BLOCK' construct is supported.
* The `STOP' and the new `ERROR STOP' statements now support all
constant expressions. Both show the signals which were signaling
at termination.
* Support for the `CONTIGUOUS' attribute.
* Support for `ALLOCATE' with `MOLD'.
* Support for the `IMPURE' attribute for procedures, which allows
for `ELEMENTAL' procedures without the restrictions of `PURE'.
* Null pointers (including `NULL()') and not-allocated variables can
be used as actual argument to optional non-pointer, non-allocatable
dummy arguments, denoting an absent argument.
* Non-pointer variables with `TARGET' attribute can be used as
actual argument to `POINTER' dummies with `INTENT(IN)'.
* Pointers including procedure pointers and those in a derived type
(pointer components) can now be initialized by a target instead of
only by `NULL'.
* The `EXIT' statement (with construct-name) can be now be used to
leave not only the `DO' but also the `ASSOCIATE', `BLOCK', `IF',
`SELECT CASE' and `SELECT TYPE' constructs.
* Internal procedures can now be used as actual argument.
* Minor features: obsolesce diagnostics for `ENTRY' with
`-std=f2008'; a line may start with a semicolon; for internal and
module procedures `END' can be used instead of `END SUBROUTINE'
and `END FUNCTION'; `SELECTED_REAL_KIND' now also takes a `RADIX'
argument; intrinsic types are supported for
`TYPE'(INTRINSIC-TYPE-SPEC); multiple type-bound procedures can be
declared in a single `PROCEDURE' statement; implied-shape arrays
are supported for named constants (`PARAMETER').

File: gfortran.info, Node: Fortran 2018 status, Prev: Fortran 2008 status, Up: Fortran standards status
4.3 Status of Fortran 2018 support
==================================
* ERROR STOP in a PURE procedure An `ERROR STOP' statement is
permitted in a `PURE' procedure.
* IMPLICIT NONE with a spec-list Support the `IMPLICIT NONE'
statement with an `implicit-none-spec-list'.
* Behavior of INQUIRE with the RECL= specifier
The behavior of the `INQUIRE' statement with the `RECL=' specifier
now conforms to Fortran 2018.
4.3.1 TS 29113 Status (Further Interoperability with C)
-------------------------------------------------------
GNU Fortran supports some of the new features of the Technical
Specification (TS) 29113 on Further Interoperability of Fortran with C.
The wiki (https://gcc.gnu.org/wiki/TS29113Status) has some information
about the current TS 29113 implementation status. In particular, the
following is implemented.
See also *note Further Interoperability of Fortran with C::.
* The `OPTIONAL' attribute is allowed for dummy arguments of
`BIND(C) procedures.'
* The `RANK' intrinsic is supported.
* GNU Fortran's implementation for variables with `ASYNCHRONOUS'
attribute is compatible with TS 29113.
* Assumed types (`TYPE(*)').
* Assumed-rank (`DIMENSION(..)').
* ISO_Fortran_binding (now in Fortran 2018 18.4) is implemented such
that conversion of the array descriptor for assumed type or
assumed rank arrays is done in the library. The include file
ISO_Fortran_binding.h is can be found in
`~prefix/lib/gcc/$target/$version'.
4.3.2 TS 18508 Status (Additional Parallel Features)
----------------------------------------------------
GNU Fortran supports the following new features of the Technical
Specification 18508 on Additional Parallel Features in Fortran:
* The new atomic ADD, CAS, FETCH and ADD/OR/XOR, OR and XOR
intrinsics.
* The `CO_MIN' and `CO_MAX' and `SUM' reduction intrinsics. And the
`CO_BROADCAST' and `CO_REDUCE' intrinsic, except that those do not
support polymorphic types or types with allocatable, pointer or
polymorphic components.
* Events (`EVENT POST', `EVENT WAIT', `EVENT_QUERY')
* Failed images (`FAIL IMAGE', `IMAGE_STATUS', `FAILED_IMAGES',
`STOPPED_IMAGES')

File: gfortran.info, Node: Compiler Characteristics, Next: Extensions, Prev: Fortran standards status, Up: Top
5 Compiler Characteristics
**************************
This chapter describes certain characteristics of the GNU Fortran
compiler, that are not specified by the Fortran standard, but which
might in some way or another become visible to the programmer.
* Menu:
* KIND Type Parameters::
* Internal representation of LOGICAL variables::
* Evaluation of logical expressions::
* MAX and MIN intrinsics with REAL NaN arguments::
* Thread-safety of the runtime library::
* Data consistency and durability::
* Files opened without an explicit ACTION= specifier::
* File operations on symbolic links::
* File format of unformatted sequential files::
* Asynchronous I/O::

File: gfortran.info, Node: KIND Type Parameters, Next: Internal representation of LOGICAL variables, Up: Compiler Characteristics
5.1 KIND Type Parameters
========================
The `KIND' type parameters supported by GNU Fortran for the primitive
data types are:
`INTEGER'
1, 2, 4, 8*, 16*, default: 4**
`LOGICAL'
1, 2, 4, 8*, 16*, default: 4**
`REAL'
4, 8, 10*, 16*, default: 4***
`COMPLEX'
4, 8, 10*, 16*, default: 4***
`DOUBLE PRECISION'
4, 8, 10*, 16*, default: 8***
`CHARACTER'
1, 4, default: 1
* not available on all systems
** unless `-fdefault-integer-8' is used
*** unless `-fdefault-real-8' is used (see *note Fortran Dialect
Options::)
The `KIND' value matches the storage size in bytes, except for
`COMPLEX' where the storage size is twice as much (or both real and
imaginary part are a real value of the given size). It is recommended
to use the *note SELECTED_CHAR_KIND::, *note SELECTED_INT_KIND:: and
*note SELECTED_REAL_KIND:: intrinsics or the `INT8', `INT16', `INT32',
`INT64', `REAL32', `REAL64', and `REAL128' parameters of the
`ISO_FORTRAN_ENV' module instead of the concrete values. The available
kind parameters can be found in the constant arrays `CHARACTER_KINDS',
`INTEGER_KINDS', `LOGICAL_KINDS' and `REAL_KINDS' in the *note
ISO_FORTRAN_ENV:: module. For C interoperability, the kind parameters
of the *note ISO_C_BINDING:: module should be used.

File: gfortran.info, Node: Internal representation of LOGICAL variables, Next: Evaluation of logical expressions, Prev: KIND Type Parameters, Up: Compiler Characteristics
5.2 Internal representation of LOGICAL variables
================================================
The Fortran standard does not specify how variables of `LOGICAL' type
are represented, beyond requiring that `LOGICAL' variables of default
kind have the same storage size as default `INTEGER' and `REAL'
variables. The GNU Fortran internal representation is as follows.
A `LOGICAL(KIND=N)' variable is represented as an `INTEGER(KIND=N)'
variable, however, with only two permissible values: `1' for `.TRUE.'
and `0' for `.FALSE.'. Any other integer value results in undefined
behavior.
See also *note Argument passing conventions:: and *note
Interoperability with C::.

File: gfortran.info, Node: Evaluation of logical expressions, Next: MAX and MIN intrinsics with REAL NaN arguments, Prev: Internal representation of LOGICAL variables, Up: Compiler Characteristics
5.3 Evaluation of logical expressions
=====================================
The Fortran standard does not require the compiler to evaluate all
parts of an expression, if they do not contribute to the final result.
For logical expressions with `.AND.' or `.OR.' operators, in
particular, GNU Fortran will optimize out function calls (even to
impure functions) if the result of the expression can be established
without them. However, since not all compilers do that, and such an
optimization can potentially modify the program flow and subsequent
results, GNU Fortran throws warnings for such situations with the
`-Wfunction-elimination' flag.

File: gfortran.info, Node: MAX and MIN intrinsics with REAL NaN arguments, Next: Thread-safety of the runtime library, Prev: Evaluation of logical expressions, Up: Compiler Characteristics
5.4 MAX and MIN intrinsics with REAL NaN arguments
==================================================
The Fortran standard does not specify what the result of the `MAX' and
`MIN' intrinsics are if one of the arguments is a `NaN'. Accordingly,
the GNU Fortran compiler does not specify that either, as this allows
for faster and more compact code to be generated. If the programmer
wishes to take some specific action in case one of the arguments is a
`NaN', it is necessary to explicitly test the arguments before calling
`MAX' or `MIN', e.g. with the `IEEE_IS_NAN' function from the intrinsic
module `IEEE_ARITHMETIC'.

File: gfortran.info, Node: Thread-safety of the runtime library, Next: Data consistency and durability, Prev: MAX and MIN intrinsics with REAL NaN arguments, Up: Compiler Characteristics
5.5 Thread-safety of the runtime library
========================================
GNU Fortran can be used in programs with multiple threads, e.g. by
using OpenMP, by calling OS thread handling functions via the
`ISO_C_BINDING' facility, or by GNU Fortran compiled library code being
called from a multi-threaded program.
The GNU Fortran runtime library, (`libgfortran'), supports being
called concurrently from multiple threads with the following exceptions.
During library initialization, the C `getenv' function is used,
which need not be thread-safe. Similarly, the `getenv' function is
used to implement the `GET_ENVIRONMENT_VARIABLE' and `GETENV'
intrinsics. It is the responsibility of the user to ensure that the
environment is not being updated concurrently when any of these actions
are taking place.
The `EXECUTE_COMMAND_LINE' and `SYSTEM' intrinsics are implemented
with the `system' function, which need not be thread-safe. It is the
responsibility of the user to ensure that `system' is not called
concurrently.
For platforms not supporting thread-safe POSIX functions, further
functionality might not be thread-safe. For details, please consult
the documentation for your operating system.
The GNU Fortran runtime library uses various C library functions that
depend on the locale, such as `strtod' and `snprintf'. In order to
work correctly in locale-aware programs that set the locale using
`setlocale', the locale is reset to the default "C" locale while
executing a formatted `READ' or `WRITE' statement. On targets
supporting the POSIX 2008 per-thread locale functions (e.g.
`newlocale', `uselocale', `freelocale'), these are used and thus the
global locale set using `setlocale' or the per-thread locales in other
threads are not affected. However, on targets lacking this
functionality, the global LC_NUMERIC locale is set to "C" during the
formatted I/O. Thus, on such targets it's not safe to call `setlocale'
concurrently from another thread while a Fortran formatted I/O
operation is in progress. Also, other threads doing something
dependent on the LC_NUMERIC locale might not work correctly if a
formatted I/O operation is in progress in another thread.

File: gfortran.info, Node: Data consistency and durability, Next: Files opened without an explicit ACTION= specifier, Prev: Thread-safety of the runtime library, Up: Compiler Characteristics
5.6 Data consistency and durability
===================================
This section contains a brief overview of data and metadata consistency
and durability issues when doing I/O.
With respect to durability, GNU Fortran makes no effort to ensure
that data is committed to stable storage. If this is required, the GNU
Fortran programmer can use the intrinsic `FNUM' to retrieve the low
level file descriptor corresponding to an open Fortran unit. Then,
using e.g. the `ISO_C_BINDING' feature, one can call the underlying
system call to flush dirty data to stable storage, such as `fsync' on
POSIX, `_commit' on MingW, or `fcntl(fd, F_FULLSYNC, 0)' on Mac OS X.
The following example shows how to call fsync:
! Declare the interface for POSIX fsync function
interface
function fsync (fd) bind(c,name="fsync")
use iso_c_binding, only: c_int
integer(c_int), value :: fd
integer(c_int) :: fsync
end function fsync
end interface
! Variable declaration
integer :: ret
! Opening unit 10
open (10,file="foo")
! ...
! Perform I/O on unit 10
! ...
! Flush and sync
flush(10)
ret = fsync(fnum(10))
! Handle possible error
if (ret /= 0) stop "Error calling FSYNC"
With respect to consistency, for regular files GNU Fortran uses
buffered I/O in order to improve performance. This buffer is flushed
automatically when full and in some other situations, e.g. when closing
a unit. It can also be explicitly flushed with the `FLUSH' statement.
Also, the buffering can be turned off with the
`GFORTRAN_UNBUFFERED_ALL' and `GFORTRAN_UNBUFFERED_PRECONNECTED'
environment variables. Special files, such as terminals and pipes, are
always unbuffered. Sometimes, however, further things may need to be
done in order to allow other processes to see data that GNU Fortran has
written, as follows.
The Windows platform supports a relaxed metadata consistency model,
where file metadata is written to the directory lazily. This means
that, for instance, the `dir' command can show a stale size for a file.
One can force a directory metadata update by closing the unit, or by
calling `_commit' on the file descriptor. Note, though, that `_commit'
will force all dirty data to stable storage, which is often a very slow
operation.
The Network File System (NFS) implements a relaxed consistency model
called open-to-close consistency. Closing a file forces dirty data and
metadata to be flushed to the server, and opening a file forces the
client to contact the server in order to revalidate cached data.
`fsync' will also force a flush of dirty data and metadata to the
server. Similar to `open' and `close', acquiring and releasing `fcntl'
file locks, if the server supports them, will also force cache
validation and flushing dirty data and metadata.

File: gfortran.info, Node: Files opened without an explicit ACTION= specifier, Next: File operations on symbolic links, Prev: Data consistency and durability, Up: Compiler Characteristics
5.7 Files opened without an explicit ACTION= specifier
======================================================
The Fortran standard says that if an `OPEN' statement is executed
without an explicit `ACTION=' specifier, the default value is processor
dependent. GNU Fortran behaves as follows:
1. Attempt to open the file with `ACTION='READWRITE''
2. If that fails, try to open with `ACTION='READ''
3. If that fails, try to open with `ACTION='WRITE''
4. If that fails, generate an error

File: gfortran.info, Node: File operations on symbolic links, Next: File format of unformatted sequential files, Prev: Files opened without an explicit ACTION= specifier, Up: Compiler Characteristics
5.8 File operations on symbolic links
=====================================
This section documents the behavior of GNU Fortran for file operations
on symbolic links, on systems that support them.
* Results of INQUIRE statements of the "inquire by file" form will
relate to the target of the symbolic link. For example,
`INQUIRE(FILE="foo",EXIST=ex)' will set EX to .TRUE. if FOO is a
symbolic link pointing to an existing file, and .FALSE. if FOO
points to an non-existing file ("dangling" symbolic link).
* Using the `OPEN' statement with a `STATUS="NEW"' specifier on a
symbolic link will result in an error condition, whether the
symbolic link points to an existing target or is dangling.
* If a symbolic link was connected, using the `CLOSE' statement with
a `STATUS="DELETE"' specifier will cause the symbolic link itself
to be deleted, not its target.

File: gfortran.info, Node: File format of unformatted sequential files, Next: Asynchronous I/O, Prev: File operations on symbolic links, Up: Compiler Characteristics
5.9 File format of unformatted sequential files
===============================================
Unformatted sequential files are stored as logical records using record
markers. Each logical record consists of one of more subrecords.
Each subrecord consists of a leading record marker, the data written
by the user program, and a trailing record marker. The record markers
are four-byte integers by default, and eight-byte integers if the
`-fmax-subrecord-length=8' option (which exists for backwards
compability only) is in effect.
The representation of the record markers is that of unformatted files
given with the `-fconvert' option, the *note CONVERT specifier:: in an
open statement or the *note GFORTRAN_CONVERT_UNIT:: environment
variable.
The maximum number of bytes of user data in a subrecord is 2147483639
(2 GiB - 9) for a four-byte record marker. This limit can be lowered
with the `-fmax-subrecord-length' option, altough this is rarely
useful. If the length of a logical record exceeds this limit, the data
is distributed among several subrecords.
The absolute of the number stored in the record markers is the number
of bytes of user data in the corresponding subrecord. If the leading
record marker of a subrecord contains a negative number, another
subrecord follows the current one. If the trailing record marker
contains a negative number, then there is a preceding subrecord.
In the most simple case, with only one subrecord per logical record,
both record markers contain the number of bytes of user data in the
record.
The format for unformatted sequential data can be duplicated using
unformatted stream, as shown in the example program for an unformatted
record containing a single subrecord:
program main
use iso_fortran_env, only: int32
implicit none
integer(int32) :: i
real, dimension(10) :: a, b
call random_number(a)
open (10,file='test.dat',form='unformatted',access='stream')
inquire (iolength=i) a
write (10) i, a, i
close (10)
open (10,file='test.dat',form='unformatted')
read (10) b
if (all (a == b)) print *,'success!'
end program main

File: gfortran.info, Node: Asynchronous I/O, Prev: File format of unformatted sequential files, Up: Compiler Characteristics
5.10 Asynchronous I/O
=====================
Asynchronous I/O is supported if the program is linked against the
POSIX thread library. If that is not the case, all I/O is performed as
synchronous. On systems which do not support pthread condition
variables, such as AIX, I/O is also performed as synchronous.
On some systems, such as Darwin or Solaris, the POSIX thread library
is always linked in, so asynchronous I/O is always performed. On other
sytems, such as Linux, it is necessary to specify `-pthread',
`-lpthread' or `-fopenmp' during the linking step.

File: gfortran.info, Node: Extensions, Next: Mixed-Language Programming, Prev: Compiler Characteristics, Up: Top
6 Extensions
************
The two sections below detail the extensions to standard Fortran that
are implemented in GNU Fortran, as well as some of the popular or
historically important extensions that are not (or not yet) implemented.
For the latter case, we explain the alternatives available to GNU
Fortran users, including replacement by standard-conforming code or GNU
extensions.
* Menu:
* Extensions implemented in GNU Fortran::
* Extensions not implemented in GNU Fortran::

File: gfortran.info, Node: Extensions implemented in GNU Fortran, Next: Extensions not implemented in GNU Fortran, Up: Extensions
6.1 Extensions implemented in GNU Fortran
=========================================
GNU Fortran implements a number of extensions over standard Fortran.
This chapter contains information on their syntax and meaning. There
are currently two categories of GNU Fortran extensions, those that
provide functionality beyond that provided by any standard, and those
that are supported by GNU Fortran purely for backward compatibility
with legacy compilers. By default, `-std=gnu' allows the compiler to
accept both types of extensions, but to warn about the use of the
latter. Specifying either `-std=f95', `-std=f2003', `-std=f2008', or
`-std=f2018' disables both types of extensions, and `-std=legacy' allows
both without warning. The special compile flag `-fdec' enables
additional compatibility extensions along with those enabled by
`-std=legacy'.
* Menu:
* Old-style kind specifications::
* Old-style variable initialization::
* Extensions to namelist::
* X format descriptor without count field::
* Commas in FORMAT specifications::
* Missing period in FORMAT specifications::
* I/O item lists::
* `Q' exponent-letter::
* BOZ literal constants::
* Real array indices::
* Unary operators::
* Implicitly convert LOGICAL and INTEGER values::
* Hollerith constants support::
* Cray pointers::
* CONVERT specifier::
* OpenMP::
* OpenACC::
* Argument list functions::
* Read/Write after EOF marker::
* STRUCTURE and RECORD::
* UNION and MAP::
* Type variants for integer intrinsics::
* AUTOMATIC and STATIC attributes::
* Extended math intrinsics::
* Form feed as whitespace::
* TYPE as an alias for PRINT::
* %LOC as an rvalue::
* .XOR. operator::
* Bitwise logical operators::
* Extended I/O specifiers::
* Legacy PARAMETER statements::
* Default exponents::

File: gfortran.info, Node: Old-style kind specifications, Next: Old-style variable initialization, Up: Extensions implemented in GNU Fortran
6.1.1 Old-style kind specifications
-----------------------------------
GNU Fortran allows old-style kind specifications in declarations. These
look like:
TYPESPEC*size x,y,z
where `TYPESPEC' is a basic type (`INTEGER', `REAL', etc.), and
where `size' is a byte count corresponding to the storage size of a
valid kind for that type. (For `COMPLEX' variables, `size' is the
total size of the real and imaginary parts.) The statement then
declares `x', `y' and `z' to be of type `TYPESPEC' with the appropriate
kind. This is equivalent to the standard-conforming declaration
TYPESPEC(k) x,y,z
where `k' is the kind parameter suitable for the intended precision.
As kind parameters are implementation-dependent, use the `KIND',
`SELECTED_INT_KIND' and `SELECTED_REAL_KIND' intrinsics to retrieve the
correct value, for instance `REAL*8 x' can be replaced by:
INTEGER, PARAMETER :: dbl = KIND(1.0d0)
REAL(KIND=dbl) :: x

File: gfortran.info, Node: Old-style variable initialization, Next: Extensions to namelist, Prev: Old-style kind specifications, Up: Extensions implemented in GNU Fortran
6.1.2 Old-style variable initialization
---------------------------------------
GNU Fortran allows old-style initialization of variables of the form:
INTEGER i/1/,j/2/
REAL x(2,2) /3*0.,1./
The syntax for the initializers is as for the `DATA' statement, but
unlike in a `DATA' statement, an initializer only applies to the
variable immediately preceding the initialization. In other words,
something like `INTEGER I,J/2,3/' is not valid. This style of
initialization is only allowed in declarations without double colons
(`::'); the double colons were introduced in Fortran 90, which also
introduced a standard syntax for initializing variables in type
declarations.
Examples of standard-conforming code equivalent to the above example
are:
! Fortran 90
INTEGER :: i = 1, j = 2
REAL :: x(2,2) = RESHAPE((/0.,0.,0.,1./),SHAPE(x))
! Fortran 77
INTEGER i, j
REAL x(2,2)
DATA i/1/, j/2/, x/3*0.,1./
Note that variables which are explicitly initialized in declarations
or in `DATA' statements automatically acquire the `SAVE' attribute.

File: gfortran.info, Node: Extensions to namelist, Next: X format descriptor without count field, Prev: Old-style variable initialization, Up: Extensions implemented in GNU Fortran
6.1.3 Extensions to namelist
----------------------------
GNU Fortran fully supports the Fortran 95 standard for namelist I/O
including array qualifiers, substrings and fully qualified derived
types. The output from a namelist write is compatible with namelist
read. The output has all names in upper case and indentation to column
1 after the namelist name. Two extensions are permitted:
Old-style use of `$' instead of `&'
$MYNML
X(:)%Y(2) = 1.0 2.0 3.0
CH(1:4) = "abcd"
$END
It should be noted that the default terminator is `/' rather than
`&END'.
Querying of the namelist when inputting from stdin. After at least
one space, entering `?' sends to stdout the namelist name and the names
of the variables in the namelist:
?
&mynml
x
x%y
ch
&end
Entering `=?' outputs the namelist to stdout, as if `WRITE(*,NML =
mynml)' had been called:
=?
&MYNML
X(1)%Y= 0.000000 , 1.000000 , 0.000000 ,
X(2)%Y= 0.000000 , 2.000000 , 0.000000 ,
X(3)%Y= 0.000000 , 3.000000 , 0.000000 ,
CH=abcd, /
To aid this dialog, when input is from stdin, errors send their
messages to stderr and execution continues, even if `IOSTAT' is set.
`PRINT' namelist is permitted. This causes an error if `-std=f95'
is used.
PROGRAM test_print
REAL, dimension (4) :: x = (/1.0, 2.0, 3.0, 4.0/)
NAMELIST /mynml/ x
PRINT mynml
END PROGRAM test_print
Expanded namelist reads are permitted. This causes an error if
`-std=f95' is used. In the following example, the first element of the
array will be given the value 0.00 and the two succeeding elements will
be given the values 1.00 and 2.00.
&MYNML
X(1,1) = 0.00 , 1.00 , 2.00
/
When writing a namelist, if no `DELIM=' is specified, by default a
double quote is used to delimit character strings. If -std=F95, F2003,
or F2008, etc, the delim status is set to 'none'. Defaulting to quotes
ensures that namelists with character strings can be subsequently read
back in accurately.

File: gfortran.info, Node: X format descriptor without count field, Next: Commas in FORMAT specifications, Prev: Extensions to namelist, Up: Extensions implemented in GNU Fortran
6.1.4 `X' format descriptor without count field
-----------------------------------------------
To support legacy codes, GNU Fortran permits the count field of the `X'
edit descriptor in `FORMAT' statements to be omitted. When omitted,
the count is implicitly assumed to be one.
PRINT 10, 2, 3
10 FORMAT (I1, X, I1)

File: gfortran.info, Node: Commas in FORMAT specifications, Next: Missing period in FORMAT specifications, Prev: X format descriptor without count field, Up: Extensions implemented in GNU Fortran
6.1.5 Commas in `FORMAT' specifications
---------------------------------------
To support legacy codes, GNU Fortran allows the comma separator to be
omitted immediately before and after character string edit descriptors
in `FORMAT' statements.
PRINT 10, 2, 3
10 FORMAT ('FOO='I1' BAR='I2)

File: gfortran.info, Node: Missing period in FORMAT specifications, Next: I/O item lists, Prev: Commas in FORMAT specifications, Up: Extensions implemented in GNU Fortran
6.1.6 Missing period in `FORMAT' specifications
-----------------------------------------------
To support legacy codes, GNU Fortran allows missing periods in format
specifications if and only if `-std=legacy' is given on the command
line. This is considered non-conforming code and is discouraged.
REAL :: value
READ(*,10) value
10 FORMAT ('F4')

File: gfortran.info, Node: I/O item lists, Next: `Q' exponent-letter, Prev: Missing period in FORMAT specifications, Up: Extensions implemented in GNU Fortran
6.1.7 I/O item lists
--------------------
To support legacy codes, GNU Fortran allows the input item list of the
`READ' statement, and the output item lists of the `WRITE' and `PRINT'
statements, to start with a comma.

File: gfortran.info, Node: `Q' exponent-letter, Next: BOZ literal constants, Prev: I/O item lists, Up: Extensions implemented in GNU Fortran
6.1.8 `Q' exponent-letter
-------------------------
GNU Fortran accepts real literal constants with an exponent-letter of
`Q', for example, `1.23Q45'. The constant is interpreted as a
`REAL(16)' entity on targets that support this type. If the target
does not support `REAL(16)' but has a `REAL(10)' type, then the
real-literal-constant will be interpreted as a `REAL(10)' entity. In
the absence of `REAL(16)' and `REAL(10)', an error will occur.

File: gfortran.info, Node: BOZ literal constants, Next: Real array indices, Prev: `Q' exponent-letter, Up: Extensions implemented in GNU Fortran
6.1.9 BOZ literal constants
---------------------------
Besides decimal constants, Fortran also supports binary (`b'), octal
(`o') and hexadecimal (`z') integer constants. The syntax is: `prefix
quote digits quote', were the prefix is either `b', `o' or `z', quote
is either `'' or `"' and the digits are for binary `0' or `1', for
octal between `0' and `7', and for hexadecimal between `0' and `F'.
(Example: `b'01011101''.)
Up to Fortran 95, BOZ literals were only allowed to initialize
integer variables in DATA statements. Since Fortran 2003 BOZ literals
are also allowed as argument of `REAL', `DBLE', `INT' and `CMPLX'; the
result is the same as if the integer BOZ literal had been converted by
`TRANSFER' to, respectively, `real', `double precision', `integer' or
`complex'. As GNU Fortran extension the intrinsic procedures `FLOAT',
`DFLOAT', `COMPLEX' and `DCMPLX' are treated alike.
As an extension, GNU Fortran allows hexadecimal BOZ literal
constants to be specified using the `X' prefix, in addition to the
standard `Z' prefix. The BOZ literal can also be specified by adding a
suffix to the string, for example, `Z'ABC'' and `'ABC'Z' are equivalent.
Furthermore, GNU Fortran allows using BOZ literal constants outside
DATA statements and the four intrinsic functions allowed by Fortran
2003. In DATA statements, in direct assignments, where the right-hand
side only contains a BOZ literal constant, and for old-style
initializers of the form `integer i /o'0173'/', the constant is
transferred as if `TRANSFER' had been used; for `COMPLEX' numbers, only
the real part is initialized unless `CMPLX' is used. In all other
cases, the BOZ literal constant is converted to an `INTEGER' value with
the largest decimal representation. This value is then converted
numerically to the type and kind of the variable in question. (For
instance, `real :: r = b'0000001' + 1' initializes `r' with `2.0'.) As
different compilers implement the extension differently, one should be
careful when doing bitwise initialization of non-integer variables.
Note that initializing an `INTEGER' variable with a statement such
as `DATA i/Z'FFFFFFFF'/' will give an integer overflow error rather
than the desired result of -1 when `i' is a 32-bit integer on a system
that supports 64-bit integers. The `-fno-range-check' option can be
used as a workaround for legacy code that initializes integers in this
manner.

File: gfortran.info, Node: Real array indices, Next: Unary operators, Prev: BOZ literal constants, Up: Extensions implemented in GNU Fortran
6.1.10 Real array indices
-------------------------
As an extension, GNU Fortran allows the use of `REAL' expressions or
variables as array indices.

File: gfortran.info, Node: Unary operators, Next: Implicitly convert LOGICAL and INTEGER values, Prev: Real array indices, Up: Extensions implemented in GNU Fortran
6.1.11 Unary operators
----------------------
As an extension, GNU Fortran allows unary plus and unary minus operators
to appear as the second operand of binary arithmetic operators without
the need for parenthesis.
X = Y * -Z

File: gfortran.info, Node: Implicitly convert LOGICAL and INTEGER values, Next: Hollerith constants support, Prev: Unary operators, Up: Extensions implemented in GNU Fortran
6.1.12 Implicitly convert `LOGICAL' and `INTEGER' values
--------------------------------------------------------
As an extension for backwards compatibility with other compilers, GNU
Fortran allows the implicit conversion of `LOGICAL' values to `INTEGER'
values and vice versa. When converting from a `LOGICAL' to an
`INTEGER', `.FALSE.' is interpreted as zero, and `.TRUE.' is
interpreted as one. When converting from `INTEGER' to `LOGICAL', the
value zero is interpreted as `.FALSE.' and any nonzero value is
interpreted as `.TRUE.'.
LOGICAL :: l
l = 1
INTEGER :: i
i = .TRUE.
However, there is no implicit conversion of `INTEGER' values in
`if'-statements, nor of `LOGICAL' or `INTEGER' values in I/O operations.

File: gfortran.info, Node: Hollerith constants support, Next: Cray pointers, Prev: Implicitly convert LOGICAL and INTEGER values, Up: Extensions implemented in GNU Fortran
6.1.13 Hollerith constants support
----------------------------------
GNU Fortran supports Hollerith constants in assignments, function
arguments, and `DATA' and `ASSIGN' statements. A Hollerith constant is
written as a string of characters preceded by an integer constant
indicating the character count, and the letter `H' or `h', and stored
in bytewise fashion in a numeric (`INTEGER', `REAL', or `complex') or
`LOGICAL' variable. The constant will be padded or truncated to fit
the size of the variable in which it is stored.
Examples of valid uses of Hollerith constants:
complex*16 x(2)
data x /16Habcdefghijklmnop, 16Hqrstuvwxyz012345/
x(1) = 16HABCDEFGHIJKLMNOP
call foo (4h abc)
Invalid Hollerith constants examples:
integer*4 a
a = 8H12345678 ! Valid, but the Hollerith constant will be truncated.
a = 0H ! At least one character is needed.
In general, Hollerith constants were used to provide a rudimentary
facility for handling character strings in early Fortran compilers,
prior to the introduction of `CHARACTER' variables in Fortran 77; in
those cases, the standard-compliant equivalent is to convert the
program to use proper character strings. On occasion, there may be a
case where the intent is specifically to initialize a numeric variable
with a given byte sequence. In these cases, the same result can be
obtained by using the `TRANSFER' statement, as in this example.
INTEGER(KIND=4) :: a
a = TRANSFER ("abcd", a) ! equivalent to: a = 4Habcd

File: gfortran.info, Node: Cray pointers, Next: CONVERT specifier, Prev: Hollerith constants support, Up: Extensions implemented in GNU Fortran
6.1.14 Cray pointers
--------------------
Cray pointers are part of a non-standard extension that provides a
C-like pointer in Fortran. This is accomplished through a pair of
variables: an integer "pointer" that holds a memory address, and a
"pointee" that is used to dereference the pointer.
Pointer/pointee pairs are declared in statements of the form:
pointer ( <pointer> , <pointee> )
or,
pointer ( <pointer1> , <pointee1> ), ( <pointer2> , <pointee2> ), ...
The pointer is an integer that is intended to hold a memory address.
The pointee may be an array or scalar. If an assumed-size array is
permitted within the scoping unit, a pointee can be an assumed-size
array. That is, the last dimension may be left unspecified by using a
`*' in place of a value. A pointee cannot be an assumed shape array.
No space is allocated for the pointee.
The pointee may have its type declared before or after the pointer
statement, and its array specification (if any) may be declared before,
during, or after the pointer statement. The pointer may be declared as
an integer prior to the pointer statement. However, some machines have
default integer sizes that are different than the size of a pointer,
and so the following code is not portable:
integer ipt
pointer (ipt, iarr)
If a pointer is declared with a kind that is too small, the compiler
will issue a warning; the resulting binary will probably not work
correctly, because the memory addresses stored in the pointers may be
truncated. It is safer to omit the first line of the above example; if
explicit declaration of ipt's type is omitted, then the compiler will
ensure that ipt is an integer variable large enough to hold a pointer.
Pointer arithmetic is valid with Cray pointers, but it is not the
same as C pointer arithmetic. Cray pointers are just ordinary
integers, so the user is responsible for determining how many bytes to
add to a pointer in order to increment it. Consider the following
example:
real target(10)
real pointee(10)
pointer (ipt, pointee)
ipt = loc (target)
ipt = ipt + 1
The last statement does not set `ipt' to the address of `target(1)',
as it would in C pointer arithmetic. Adding `1' to `ipt' just adds one
byte to the address stored in `ipt'.
Any expression involving the pointee will be translated to use the
value stored in the pointer as the base address.
To get the address of elements, this extension provides an intrinsic
function `LOC()'. The `LOC()' function is equivalent to the `&'
operator in C, except the address is cast to an integer type:
real ar(10)
pointer(ipt, arpte(10))
real arpte
ipt = loc(ar) ! Makes arpte is an alias for ar
arpte(1) = 1.0 ! Sets ar(1) to 1.0
The pointer can also be set by a call to the `MALLOC' intrinsic (see
*note MALLOC::).
Cray pointees often are used to alias an existing variable. For
example:
integer target(10)
integer iarr(10)
pointer (ipt, iarr)
ipt = loc(target)
As long as `ipt' remains unchanged, `iarr' is now an alias for
`target'. The optimizer, however, will not detect this aliasing, so it
is unsafe to use `iarr' and `target' simultaneously. Using a pointee
in any way that violates the Fortran aliasing rules or assumptions is
illegal. It is the user's responsibility to avoid doing this; the
compiler works under the assumption that no such aliasing occurs.
Cray pointers will work correctly when there is no aliasing (i.e.,
when they are used to access a dynamically allocated block of memory),
and also in any routine where a pointee is used, but any variable with
which it shares storage is not used. Code that violates these rules
may not run as the user intends. This is not a bug in the optimizer;
any code that violates the aliasing rules is illegal. (Note that this
is not unique to GNU Fortran; any Fortran compiler that supports Cray
pointers will "incorrectly" optimize code with illegal aliasing.)
There are a number of restrictions on the attributes that can be
applied to Cray pointers and pointees. Pointees may not have the
`ALLOCATABLE', `INTENT', `OPTIONAL', `DUMMY', `TARGET', `INTRINSIC', or
`POINTER' attributes. Pointers may not have the `DIMENSION',
`POINTER', `TARGET', `ALLOCATABLE', `EXTERNAL', or `INTRINSIC'
attributes, nor may they be function results. Pointees may not occur
in more than one pointer statement. A pointee cannot be a pointer.
Pointees cannot occur in equivalence, common, or data statements.
A Cray pointer may also point to a function or a subroutine. For
example, the following excerpt is valid:
implicit none
external sub
pointer (subptr,subpte)
external subpte
subptr = loc(sub)
call subpte()
[...]
subroutine sub
[...]
end subroutine sub
A pointer may be modified during the course of a program, and this
will change the location to which the pointee refers. However, when
pointees are passed as arguments, they are treated as ordinary
variables in the invoked function. Subsequent changes to the pointer
will not change the base address of the array that was passed.

File: gfortran.info, Node: CONVERT specifier, Next: OpenMP, Prev: Cray pointers, Up: Extensions implemented in GNU Fortran
6.1.15 `CONVERT' specifier
--------------------------
GNU Fortran allows the conversion of unformatted data between little-
and big-endian representation to facilitate moving of data between
different systems. The conversion can be indicated with the `CONVERT'
specifier on the `OPEN' statement. *Note GFORTRAN_CONVERT_UNIT::, for
an alternative way of specifying the data format via an environment
variable.
Valid values for `CONVERT' are:
`CONVERT='NATIVE'' Use the native format. This is the default.
`CONVERT='SWAP'' Swap between little- and big-endian.
`CONVERT='LITTLE_ENDIAN'' Use the little-endian representation for
unformatted files.
`CONVERT='BIG_ENDIAN'' Use the big-endian representation for
unformatted files.
Using the option could look like this:
open(file='big.dat',form='unformatted',access='sequential', &
convert='big_endian')
The value of the conversion can be queried by using
`INQUIRE(CONVERT=ch)'. The values returned are `'BIG_ENDIAN'' and
`'LITTLE_ENDIAN''.
`CONVERT' works between big- and little-endian for `INTEGER' values
of all supported kinds and for `REAL' on IEEE systems of kinds 4 and 8.
Conversion between different "extended double" types on different
architectures such as m68k and x86_64, which GNU Fortran supports as
`REAL(KIND=10)' and `REAL(KIND=16)', will probably not work.
_Note that the values specified via the GFORTRAN_CONVERT_UNIT
environment variable will override the CONVERT specifier in the open
statement_. This is to give control over data formats to users who do
not have the source code of their program available.
Using anything but the native representation for unformatted data
carries a significant speed overhead. If speed in this area matters to
you, it is best if you use this only for data that needs to be portable.

File: gfortran.info, Node: OpenMP, Next: OpenACC, Prev: CONVERT specifier, Up: Extensions implemented in GNU Fortran
6.1.16 OpenMP
-------------
OpenMP (Open Multi-Processing) is an application programming interface
(API) that supports multi-platform shared memory multiprocessing
programming in C/C++ and Fortran on many architectures, including Unix
and Microsoft Windows platforms. It consists of a set of compiler
directives, library routines, and environment variables that influence
run-time behavior.
GNU Fortran strives to be compatible to the OpenMP Application
Program Interface v4.5 (http://openmp.org/wp/openmp-specifications/).
To enable the processing of the OpenMP directive `!$omp' in
free-form source code; the `c$omp', `*$omp' and `!$omp' directives in
fixed form; the `!$' conditional compilation sentinels in free form;
and the `c$', `*$' and `!$' sentinels in fixed form, `gfortran' needs
to be invoked with the `-fopenmp'. This also arranges for automatic
linking of the GNU Offloading and Multi Processing Runtime Library
*note libgomp: (libgomp)Top.
The OpenMP Fortran runtime library routines are provided both in a
form of a Fortran 90 module named `omp_lib' and in a form of a Fortran
`include' file named `omp_lib.h'.
An example of a parallelized loop taken from Appendix A.1 of the
OpenMP Application Program Interface v2.5:
SUBROUTINE A1(N, A, B)
INTEGER I, N
REAL B(N), A(N)
!$OMP PARALLEL DO !I is private by default
DO I=2,N
B(I) = (A(I) + A(I-1)) / 2.0
ENDDO
!$OMP END PARALLEL DO
END SUBROUTINE A1
Please note:
* `-fopenmp' implies `-frecursive', i.e., all local arrays will be
allocated on the stack. When porting existing code to OpenMP,
this may lead to surprising results, especially to segmentation
faults if the stacksize is limited.
* On glibc-based systems, OpenMP enabled applications cannot be
statically linked due to limitations of the underlying
pthreads-implementation. It might be possible to get a working
solution if `-Wl,--whole-archive -lpthread -Wl,--no-whole-archive'
is added to the command line. However, this is not supported by
`gcc' and thus not recommended.

File: gfortran.info, Node: OpenACC, Next: Argument list functions, Prev: OpenMP, Up: Extensions implemented in GNU Fortran
6.1.17 OpenACC
--------------
OpenACC is an application programming interface (API) that supports
offloading of code to accelerator devices. It consists of a set of
compiler directives, library routines, and environment variables that
influence run-time behavior.
GNU Fortran strives to be compatible to the OpenACC Application
Programming Interface v2.0 (http://www.openacc.org/).
To enable the processing of the OpenACC directive `!$acc' in
free-form source code; the `c$acc', `*$acc' and `!$acc' directives in
fixed form; the `!$' conditional compilation sentinels in free form;
and the `c$', `*$' and `!$' sentinels in fixed form, `gfortran' needs
to be invoked with the `-fopenacc'. This also arranges for automatic
linking of the GNU Offloading and Multi Processing Runtime Library
*note libgomp: (libgomp)Top.
The OpenACC Fortran runtime library routines are provided both in a
form of a Fortran 90 module named `openacc' and in a form of a Fortran
`include' file named `openacc_lib.h'.
Note that this is an experimental feature, incomplete, and subject to
change in future versions of GCC. See
`https://gcc.gnu.org/wiki/OpenACC' for more information.

File: gfortran.info, Node: Argument list functions, Next: Read/Write after EOF marker, Prev: OpenACC, Up: Extensions implemented in GNU Fortran
6.1.18 Argument list functions `%VAL', `%REF' and `%LOC'
--------------------------------------------------------
GNU Fortran supports argument list functions `%VAL', `%REF' and `%LOC'
statements, for backward compatibility with g77. It is recommended
that these should be used only for code that is accessing facilities
outside of GNU Fortran, such as operating system or windowing
facilities. It is best to constrain such uses to isolated portions of
a program-portions that deal specifically and exclusively with
low-level, system-dependent facilities. Such portions might well
provide a portable interface for use by the program as a whole, but are
themselves not portable, and should be thoroughly tested each time they
are rebuilt using a new compiler or version of a compiler.
`%VAL' passes a scalar argument by value, `%REF' passes it by
reference and `%LOC' passes its memory location. Since gfortran
already passes scalar arguments by reference, `%REF' is in effect a
do-nothing. `%LOC' has the same effect as a Fortran pointer.
An example of passing an argument by value to a C subroutine foo.:
C
C prototype void foo_ (float x);
C
external foo
real*4 x
x = 3.14159
call foo (%VAL (x))
end
For details refer to the g77 manual
`https://gcc.gnu.org/onlinedocs/gcc-3.4.6/g77/index.html#Top'.
Also, `c_by_val.f' and its partner `c_by_val.c' of the GNU Fortran
testsuite are worth a look.

File: gfortran.info, Node: Read/Write after EOF marker, Next: STRUCTURE and RECORD, Prev: Argument list functions, Up: Extensions implemented in GNU Fortran
6.1.19 Read/Write after EOF marker
----------------------------------
Some legacy codes rely on allowing `READ' or `WRITE' after the EOF file
marker in order to find the end of a file. GNU Fortran normally rejects
these codes with a run-time error message and suggests the user
consider `BACKSPACE' or `REWIND' to properly position the file before
the EOF marker. As an extension, the run-time error may be disabled
using -std=legacy.

File: gfortran.info, Node: STRUCTURE and RECORD, Next: UNION and MAP, Prev: Read/Write after EOF marker, Up: Extensions implemented in GNU Fortran
6.1.20 `STRUCTURE' and `RECORD'
-------------------------------
Record structures are a pre-Fortran-90 vendor extension to create
user-defined aggregate data types. Support for record structures in GNU
Fortran can be enabled with the `-fdec-structure' compile flag. If you
have a choice, you should instead use Fortran 90's "derived types",
which have a different syntax.
In many cases, record structures can easily be converted to derived
types. To convert, replace `STRUCTURE /'STRUCTURE-NAME`/' by `TYPE'
TYPE-NAME. Additionally, replace `RECORD /'STRUCTURE-NAME`/' by
`TYPE('TYPE-NAME`)'. Finally, in the component access, replace the
period (`.') by the percent sign (`%').
Here is an example of code using the non portable record structure
syntax:
! Declaring a structure named ``item'' and containing three fields:
! an integer ID, an description string and a floating-point price.
STRUCTURE /item/
INTEGER id
CHARACTER(LEN=200) description
REAL price
END STRUCTURE
! Define two variables, an single record of type ``item''
! named ``pear'', and an array of items named ``store_catalog''
RECORD /item/ pear, store_catalog(100)
! We can directly access the fields of both variables
pear.id = 92316
pear.description = "juicy D'Anjou pear"
pear.price = 0.15
store_catalog(7).id = 7831
store_catalog(7).description = "milk bottle"
store_catalog(7).price = 1.2
! We can also manipulate the whole structure
store_catalog(12) = pear
print *, store_catalog(12)
This code can easily be rewritten in the Fortran 90 syntax as following:
! ``STRUCTURE /name/ ... END STRUCTURE'' becomes
! ``TYPE name ... END TYPE''
TYPE item
INTEGER id
CHARACTER(LEN=200) description
REAL price
END TYPE
! ``RECORD /name/ variable'' becomes ``TYPE(name) variable''
TYPE(item) pear, store_catalog(100)
! Instead of using a dot (.) to access fields of a record, the
! standard syntax uses a percent sign (%)
pear%id = 92316
pear%description = "juicy D'Anjou pear"
pear%price = 0.15
store_catalog(7)%id = 7831
store_catalog(7)%description = "milk bottle"
store_catalog(7)%price = 1.2
! Assignments of a whole variable do not change
store_catalog(12) = pear
print *, store_catalog(12)
GNU Fortran implements STRUCTURES like derived types with the following
rules and exceptions:
* Structures act like derived types with the `SEQUENCE' attribute.
Otherwise they may contain no specifiers.
* Structures may contain a special field with the name `%FILL'.
This will create an anonymous component which cannot be accessed
but occupies space just as if a component of the same type was
declared in its place, useful for alignment purposes. As an
example, the following structure will consist of at least sixteen
bytes:
structure /padded/
character(4) start
character(8) %FILL
character(4) end
end structure
* Structures may share names with other symbols. For example, the
following is invalid for derived types, but valid for structures:
structure /header/
! ...
end structure
record /header/ header
* Structure types may be declared nested within another parent
structure. The syntax is:
structure /type-name/
...
structure [/<type-name>/] <field-list>
...
The type name may be ommitted, in which case the structure type
itself is anonymous, and other structures of the same type cannot
be instantiated. The following shows some examples:
structure /appointment/
! nested structure definition: app_time is an array of two 'time'
structure /time/ app_time (2)
integer(1) hour, minute
end structure
character(10) memo
end structure
! The 'time' structure is still usable
record /time/ now
now = time(5, 30)
...
structure /appointment/
! anonymous nested structure definition
structure start, end
integer(1) hour, minute
end structure
character(10) memo
end structure
* Structures may contain `UNION' blocks. For more detail see the
section on *note UNION and MAP::.
* Structures support old-style initialization of components, like
those described in *note Old-style variable initialization::. For
array initializers, an initializer may contain a repeat
specification of the form `<literal-integer> *
<constant-initializer>'. The value of the integer indicates the
number of times to repeat the constant initializer when expanding
the initializer list.

File: gfortran.info, Node: UNION and MAP, Next: Type variants for integer intrinsics, Prev: STRUCTURE and RECORD, Up: Extensions implemented in GNU Fortran
6.1.21 `UNION' and `MAP'
------------------------
Unions are an old vendor extension which were commonly used with the
non-standard *note STRUCTURE and RECORD:: extensions. Use of `UNION' and
`MAP' is automatically enabled with `-fdec-structure'.
A `UNION' declaration occurs within a structure; within the
definition of each union is a number of `MAP' blocks. Each `MAP' shares
storage with its sibling maps (in the same union), and the size of the
union is the size of the largest map within it, just as with unions in
C. The major difference is that component references do not indicate
which union or map the component is in (the compiler gets to figure
that out).
Here is a small example:
structure /myunion/
union
map
character(2) w0, w1, w2
end map
map
character(6) long
end map
end union
end structure
record /myunion/ rec
! After this assignment...
rec.long = 'hello!'
! The following is true:
! rec.w0 === 'he'
! rec.w1 === 'll'
! rec.w2 === 'o!'
The two maps share memory, and the size of the union is ultimately
six bytes:
0 1 2 3 4 5 6 Byte offset
-------------------------------
| | | | | | |
-------------------------------
^ W0 ^ W1 ^ W2 ^
\-------/ \-------/ \-------/
^ LONG ^
\---------------------------/
Following is an example mirroring the layout of an Intel x86_64
register:
structure /reg/
union ! U0 ! rax
map
character(16) rx
end map
map
character(8) rh ! rah
union ! U1
map
character(8) rl ! ral
end map
map
character(8) ex ! eax
end map
map
character(4) eh ! eah
union ! U2
map
character(4) el ! eal
end map
map
character(4) x ! ax
end map
map
character(2) h ! ah
character(2) l ! al
end map
end union
end map
end union
end map
end union
end structure
record /reg/ a
! After this assignment...
a.rx = 'AAAAAAAA.BBB.C.D'
! The following is true:
a.rx === 'AAAAAAAA.BBB.C.D'
a.rh === 'AAAAAAAA'
a.rl === '.BBB.C.D'
a.ex === '.BBB.C.D'
a.eh === '.BBB'
a.el === '.C.D'
a.x === '.C.D'
a.h === '.C'
a.l === '.D'

File: gfortran.info, Node: Type variants for integer intrinsics, Next: AUTOMATIC and STATIC attributes, Prev: UNION and MAP, Up: Extensions implemented in GNU Fortran
6.1.22 Type variants for integer intrinsics
-------------------------------------------
Similar to the D/C prefixes to real functions to specify the
input/output types, GNU Fortran offers B/I/J/K prefixes to integer
functions for compatibility with DEC programs. The types implied by
each are:
`B' - `INTEGER(kind=1)'
`I' - `INTEGER(kind=2)'
`J' - `INTEGER(kind=4)'
`K' - `INTEGER(kind=8)'
GNU Fortran supports these with the flag `-fdec-intrinsic-ints'.
Intrinsics for which prefixed versions are available and in what form
are noted in *note Intrinsic Procedures::. The complete list of
supported intrinsics is here:
Intrinsic B I J K
---------------------------------------------------------------------------
`*note ABS::' `BABS' `IIABS' `JIABS' `KIABS'
`*note `BBTEST' `BITEST' `BJTEST' `BKTEST'
BTEST::'
`*note IAND::' `BIAND' `IIAND' `JIAND' `KIAND'
`*note `BBCLR' `IIBCLR' `JIBCLR' `KIBCLR'
IBCLR::'
`*note `BBITS' `IIBITS' `JIBITS' `KIBITS'
IBITS::'
`*note `BBSET' `IIBSET' `JIBSET' `KIBSET'
IBSET::'
`*note IEOR::' `BIEOR' `IIEOR' `JIEOR' `KIEOR'
`*note IOR::' `BIOR' `IIOR' `JIOR' `KIOR'
`*note `BSHFT' `IISHFT' `JISHFT' `KISHFT'
ISHFT::'
`*note `BSHFTC' `IISHFTC' `JISHFTC' `KISHFTC'
ISHFTC::'
`*note MOD::' `BMOD' `IMOD' `JMOD' `KMOD'
`*note NOT::' `BNOT' `INOT' `JNOT' `KNOT'
`*note REAL::' `--' `FLOATI' `FLOATJ' `FLOATK'

File: gfortran.info, Node: AUTOMATIC and STATIC attributes, Next: Extended math intrinsics, Prev: Type variants for integer intrinsics, Up: Extensions implemented in GNU Fortran
6.1.23 `AUTOMATIC' and `STATIC' attributes
------------------------------------------
With `-fdec-static' GNU Fortran supports the DEC extended attributes
`STATIC' and `AUTOMATIC' to provide explicit specification of entity
storage. These follow the syntax of the Fortran standard `SAVE'
attribute.
`STATIC' is exactly equivalent to `SAVE', and specifies that an
entity should be allocated in static memory. As an example, `STATIC'
local variables will retain their values across multiple calls to a
function.
Entities marked `AUTOMATIC' will be stack automatic whenever
possible. `AUTOMATIC' is the default for local variables smaller than
`-fmax-stack-var-size', unless `-fno-automatic' is given. This
attribute overrides `-fno-automatic', `-fmax-stack-var-size', and
blanket `SAVE' statements.
Examples:
subroutine f
integer, automatic :: i ! automatic variable
integer x, y ! static variables
save
...
endsubroutine
subroutine f
integer a, b, c, x, y, z
static :: x
save y
automatic z, c
! a, b, c, and z are automatic
! x and y are static
endsubroutine
! Compiled with -fno-automatic
subroutine f
integer a, b, c, d
automatic :: a
! a is automatic; b, c, and d are static
endsubroutine

File: gfortran.info, Node: Extended math intrinsics, Next: Form feed as whitespace, Prev: AUTOMATIC and STATIC attributes, Up: Extensions implemented in GNU Fortran
6.1.24 Extended math intrinsics
-------------------------------
GNU Fortran supports an extended list of mathematical intrinsics with
the compile flag `-fdec-math' for compatability with legacy code.
These intrinsics are described fully in *note Intrinsic Procedures::
where it is noted that they are extensions and should be avoided
whenever possible.
Specifically, `-fdec-math' enables the *note COTAN:: intrinsic, and
trigonometric intrinsics which accept or produce values in degrees
instead of radians. Here is a summary of the new intrinsics:
Radians Degrees
--------------------------------------------------------------------------
`*note ACOS::' `*note ACOSD::'*
`*note ASIN::' `*note ASIND::'*
`*note ATAN::' `*note ATAND::'*
`*note ATAN2::' `*note ATAN2D::'*
`*note COS::' `*note COSD::'*
`*note COTAN::'* `*note COTAND::'*
`*note SIN::' `*note SIND::'*
`*note TAN::' `*note TAND::'*
* Enabled with `-fdec-math'.
For advanced users, it may be important to know the implementation
of these functions. They are simply wrappers around the standard radian
functions, which have more accurate builtin versions. These functions
convert their arguments (or results) to degrees (or radians) by taking
the value modulus 360 (or 2*pi) and then multiplying it by a constant
radian-to-degree (or degree-to-radian) factor, as appropriate. The
factor is computed at compile-time as 180/pi (or pi/180).

File: gfortran.info, Node: Form feed as whitespace, Next: TYPE as an alias for PRINT, Prev: Extended math intrinsics, Up: Extensions implemented in GNU Fortran
6.1.25 Form feed as whitespace
------------------------------
Historically, legacy compilers allowed insertion of form feed
characters ('\f', ASCII 0xC) at the beginning of lines for formatted
output to line printers, though the Fortran standard does not mention
this. GNU Fortran supports the interpretation of form feed characters
in source as whitespace for compatibility.

File: gfortran.info, Node: TYPE as an alias for PRINT, Next: %LOC as an rvalue, Prev: Form feed as whitespace, Up: Extensions implemented in GNU Fortran
6.1.26 TYPE as an alias for PRINT
---------------------------------
For compatibility, GNU Fortran will interpret `TYPE' statements as
`PRINT' statements with the flag `-fdec'. With this flag asserted, the
following two examples are equivalent:
TYPE *, 'hello world'
PRINT *, 'hello world'

File: gfortran.info, Node: %LOC as an rvalue, Next: .XOR. operator, Prev: TYPE as an alias for PRINT, Up: Extensions implemented in GNU Fortran
6.1.27 %LOC as an rvalue
------------------------
Normally `%LOC' is allowed only in parameter lists. However the
intrinsic function `LOC' does the same thing, and is usable as the
right-hand-side of assignments. For compatibility, GNU Fortran supports
the use of `%LOC' as an alias for the builtin `LOC' with `-std=legacy'.
With this feature enabled the following two examples are equivalent:
integer :: i, l
l = %loc(i)
call sub(l)
integer :: i
call sub(%loc(i))

File: gfortran.info, Node: .XOR. operator, Next: Bitwise logical operators, Prev: %LOC as an rvalue, Up: Extensions implemented in GNU Fortran
6.1.28 .XOR. operator
---------------------
GNU Fortran supports `.XOR.' as a logical operator with `-std=legacy'
for compatibility with legacy code. `.XOR.' is equivalent to `.NEQV.'.
That is, the output is true if and only if the inputs differ.

File: gfortran.info, Node: Bitwise logical operators, Next: Extended I/O specifiers, Prev: .XOR. operator, Up: Extensions implemented in GNU Fortran
6.1.29 Bitwise logical operators
--------------------------------
With `-fdec', GNU Fortran relaxes the type constraints on logical
operators to allow integer operands, and performs the corresponding
bitwise operation instead. This flag is for compatibility only, and
should be avoided in new code. Consider:
INTEGER :: i, j
i = z'33'
j = z'cc'
print *, i .AND. j
In this example, compiled with `-fdec', GNU Fortran will replace the
`.AND.' operation with a call to the intrinsic `*note IAND::' function,
yielding the bitwise-and of `i' and `j'.
Note that this conversion will occur if at least one operand is of
integral type. As a result, a logical operand will be converted to an
integer when the other operand is an integer in a logical operation.
In this case, `.TRUE.' is converted to `1' and `.FALSE.' to `0'.
Here is the mapping of logical operator to bitwise intrinsic used
with `-fdec':
Operator Intrinsic Bitwise operation
---------------------------------------------------------------------------
`.NOT.' `*note NOT::' complement
`.AND.' `*note IAND::' intersection
`.OR.' `*note IOR::' union
`.NEQV.' `*note IEOR::' exclusive or
`.EQV.' `*note complement of exclusive or
NOT::(*note
IEOR::)'

File: gfortran.info, Node: Extended I/O specifiers, Next: Legacy PARAMETER statements, Prev: Bitwise logical operators, Up: Extensions implemented in GNU Fortran
6.1.30 Extended I/O specifiers
------------------------------
GNU Fortran supports the additional legacy I/O specifiers
`CARRIAGECONTROL', `READONLY', and `SHARE' with the compile flag
`-fdec', for compatibility.
`CARRIAGECONTROL'
The `CARRIAGECONTROL' specifier allows a user to control line
termination settings between output records for an I/O unit. The
specifier has no meaning for readonly files. When
`CARRAIGECONTROL' is specified upon opening a unit for formatted
writing, the exact `CARRIAGECONTROL' setting determines what
characters to write between output records. The syntax is:
OPEN(..., CARRIAGECONTROL=cc)
Where _cc_ is a character expression that evaluates to one of the
following values:
`'LIST'' One line feed between records (default)
`'FORTRAN'' Legacy interpretation of the first character (see
below)
`'NONE'' No separator between records
With `CARRIAGECONTROL='FORTRAN'', when a record is written, the
first character of the input record is not written, and instead
determines the output record separator as follows:
Leading character Meaning Output separating
character(s)
----------------------------------------------------------------------
`'+'' Overprinting Carriage return only
`'-'' New line Line feed and carriage
return
`'0'' Skip line Two line feeds and
carriage return
`'1'' New page Form feed and carriage
return
`'$'' Prompting Line feed (no carriage
return)
`CHAR(0)' Overprinting (no None
advance)
`READONLY'
The `READONLY' specifier may be given upon opening a unit, and is
equivalent to specifying `ACTION='READ'', except that the file may
not be deleted on close (i.e. `CLOSE' with `STATUS="DELETE"'). The
syntax is:
`OPEN(..., READONLY)'
`SHARE'
The `SHARE' specifier allows system-level locking on a unit upon
opening it for controlled access from multiple processes/threads.
The `SHARE' specifier has several forms:
OPEN(..., SHARE=sh)
OPEN(..., SHARED)
OPEN(..., NOSHARED)
Where _sh_ in the first form is a character expression that
evaluates to a value as seen in the table below. The latter two
forms are aliases for particular values of _sh_:
Explicit form Short form Meaning
----------------------------------------------------------------------
`SHARE='DENYRW'' `NOSHARED' Exclusive (write) lock
`SHARE='DENYNONE'' `SHARED' Shared (read) lock
In general only one process may hold an exclusive (write) lock for
a given file at a time, whereas many processes may hold shared
(read) locks for the same file.
The behavior of locking may vary with your operating system. On
POSIX systems, locking is implemented with `fcntl'. Consult your
corresponding operating system's manual pages for further details.
Locking via `SHARE=' is not supported on other systems.

File: gfortran.info, Node: Legacy PARAMETER statements, Next: Default exponents, Prev: Extended I/O specifiers, Up: Extensions implemented in GNU Fortran
6.1.31 Legacy PARAMETER statements
----------------------------------
For compatibility, GNU Fortran supports legacy PARAMETER statements
without parentheses with `-std=legacy'. A warning is emitted if used
with `-std=gnu', and an error is acknowledged with a real Fortran
standard flag (`-std=f95', etc...). These statements take the
following form:
implicit real (E)
parameter e = 2.718282
real c
parameter c = 3.0e8

File: gfortran.info, Node: Default exponents, Prev: Legacy PARAMETER statements, Up: Extensions implemented in GNU Fortran
6.1.32 Default exponents
------------------------
For compatibility, GNU Fortran supports a default exponent of zero in
real constants with `-fdec'. For example, `9e' would be interpreted as
`9e0', rather than an error.

File: gfortran.info, Node: Extensions not implemented in GNU Fortran, Prev: Extensions implemented in GNU Fortran, Up: Extensions
6.2 Extensions not implemented in GNU Fortran
=============================================
The long history of the Fortran language, its wide use and broad
userbase, the large number of different compiler vendors and the lack of
some features crucial to users in the first standards have lead to the
existence of a number of important extensions to the language. While
some of the most useful or popular extensions are supported by the GNU
Fortran compiler, not all existing extensions are supported. This
section aims at listing these extensions and offering advice on how
best make code that uses them running with the GNU Fortran compiler.
* Menu:
* ENCODE and DECODE statements::
* Variable FORMAT expressions::
* Alternate complex function syntax::
* Volatile COMMON blocks::
* OPEN( ... NAME=)::
* Q edit descriptor::

File: gfortran.info, Node: ENCODE and DECODE statements, Next: Variable FORMAT expressions, Up: Extensions not implemented in GNU Fortran
6.2.1 `ENCODE' and `DECODE' statements
--------------------------------------
GNU Fortran does not support the `ENCODE' and `DECODE' statements.
These statements are best replaced by `READ' and `WRITE' statements
involving internal files (`CHARACTER' variables and arrays), which have
been part of the Fortran standard since Fortran 77. For example,
replace a code fragment like
INTEGER*1 LINE(80)
REAL A, B, C
c ... Code that sets LINE
DECODE (80, 9000, LINE) A, B, C
9000 FORMAT (1X, 3(F10.5))
with the following:
CHARACTER(LEN=80) LINE
REAL A, B, C
c ... Code that sets LINE
READ (UNIT=LINE, FMT=9000) A, B, C
9000 FORMAT (1X, 3(F10.5))
Similarly, replace a code fragment like
INTEGER*1 LINE(80)
REAL A, B, C
c ... Code that sets A, B and C
ENCODE (80, 9000, LINE) A, B, C
9000 FORMAT (1X, 'OUTPUT IS ', 3(F10.5))
with the following:
CHARACTER(LEN=80) LINE
REAL A, B, C
c ... Code that sets A, B and C
WRITE (UNIT=LINE, FMT=9000) A, B, C
9000 FORMAT (1X, 'OUTPUT IS ', 3(F10.5))

File: gfortran.info, Node: Variable FORMAT expressions, Next: Alternate complex function syntax, Prev: ENCODE and DECODE statements, Up: Extensions not implemented in GNU Fortran
6.2.2 Variable `FORMAT' expressions
-----------------------------------
A variable `FORMAT' expression is format statement which includes angle
brackets enclosing a Fortran expression: `FORMAT(I<N>)'. GNU Fortran
does not support this legacy extension. The effect of variable format
expressions can be reproduced by using the more powerful (and standard)
combination of internal output and string formats. For example,
replace a code fragment like this:
WRITE(6,20) INT1
20 FORMAT(I<N+1>)
with the following:
c Variable declaration
CHARACTER(LEN=20) FMT
c
c Other code here...
c
WRITE(FMT,'("(I", I0, ")")') N+1
WRITE(6,FMT) INT1
or with:
c Variable declaration
CHARACTER(LEN=20) FMT
c
c Other code here...
c
WRITE(FMT,*) N+1
WRITE(6,"(I" // ADJUSTL(FMT) // ")") INT1

File: gfortran.info, Node: Alternate complex function syntax, Next: Volatile COMMON blocks, Prev: Variable FORMAT expressions, Up: Extensions not implemented in GNU Fortran
6.2.3 Alternate complex function syntax
---------------------------------------
Some Fortran compilers, including `g77', let the user declare complex
functions with the syntax `COMPLEX FUNCTION name*16()', as well as
`COMPLEX*16 FUNCTION name()'. Both are non-standard, legacy
extensions. `gfortran' accepts the latter form, which is more common,
but not the former.

File: gfortran.info, Node: Volatile COMMON blocks, Next: OPEN( ... NAME=), Prev: Alternate complex function syntax, Up: Extensions not implemented in GNU Fortran
6.2.4 Volatile `COMMON' blocks
------------------------------
Some Fortran compilers, including `g77', let the user declare `COMMON'
with the `VOLATILE' attribute. This is invalid standard Fortran syntax
and is not supported by `gfortran'. Note that `gfortran' accepts
`VOLATILE' variables in `COMMON' blocks since revision 4.3.

File: gfortran.info, Node: OPEN( ... NAME=), Next: Q edit descriptor, Prev: Volatile COMMON blocks, Up: Extensions not implemented in GNU Fortran
6.2.5 `OPEN( ... NAME=)'
------------------------
Some Fortran compilers, including `g77', let the user declare `OPEN(
... NAME=)'. This is invalid standard Fortran syntax and is not
supported by `gfortran'. `OPEN( ... NAME=)' should be replaced with
`OPEN( ... FILE=)'.

File: gfortran.info, Node: Q edit descriptor, Prev: OPEN( ... NAME=), Up: Extensions not implemented in GNU Fortran
6.2.6 `Q' edit descriptor
-------------------------
Some Fortran compilers provide the `Q' edit descriptor, which transfers
the number of characters left within an input record into an integer
variable.
A direct replacement of the `Q' edit descriptor is not available in
`gfortran'. How to replicate its functionality using
standard-conforming code depends on what the intent of the original
code is.
Options to replace `Q' may be to read the whole line into a
character variable and then counting the number of non-blank characters
left using `LEN_TRIM'. Another method may be to use formatted stream,
read the data up to the position where the `Q' descriptor occurred, use
`INQUIRE' to get the file position, count the characters up to the next
`NEW_LINE' and then start reading from the position marked previously.

File: gfortran.info, Node: Mixed-Language Programming, Next: Coarray Programming, Prev: Extensions, Up: Top
7 Mixed-Language Programming
****************************
* Menu:
* Interoperability with C::
* GNU Fortran Compiler Directives::
* Non-Fortran Main Program::
* Naming and argument-passing conventions::
This chapter is about mixed-language interoperability, but also
applies if one links Fortran code compiled by different compilers. In
most cases, use of the C Binding features of the Fortran 2003 standard
is sufficient, and their use is highly recommended.

File: gfortran.info, Node: Interoperability with C, Next: GNU Fortran Compiler Directives, Up: Mixed-Language Programming
7.1 Interoperability with C
===========================
* Menu:
* Intrinsic Types::
* Derived Types and struct::
* Interoperable Global Variables::
* Interoperable Subroutines and Functions::
* Working with Pointers::
* Further Interoperability of Fortran with C::
Since Fortran 2003 (ISO/IEC 1539-1:2004(E)) there is a standardized
way to generate procedure and derived-type declarations and global
variables which are interoperable with C (ISO/IEC 9899:1999). The
`bind(C)' attribute has been added to inform the compiler that a symbol
shall be interoperable with C; also, some constraints are added. Note,
however, that not all C features have a Fortran equivalent or vice
versa. For instance, neither C's unsigned integers nor C's functions
with variable number of arguments have an equivalent in Fortran.
Note that array dimensions are reversely ordered in C and that
arrays in C always start with index 0 while in Fortran they start by
default with 1. Thus, an array declaration `A(n,m)' in Fortran matches
`A[m][n]' in C and accessing the element `A(i,j)' matches
`A[j-1][i-1]'. The element following `A(i,j)' (C: `A[j-1][i-1]';
assuming i < n) in memory is `A(i+1,j)' (C: `A[j-1][i]').

File: gfortran.info, Node: Intrinsic Types, Next: Derived Types and struct, Up: Interoperability with C
7.1.1 Intrinsic Types
---------------------
In order to ensure that exactly the same variable type and kind is used
in C and Fortran, the named constants shall be used which are defined
in the `ISO_C_BINDING' intrinsic module. That module contains named
constants for kind parameters and character named constants for the
escape sequences in C. For a list of the constants, see *note
ISO_C_BINDING::.
For logical types, please note that the Fortran standard only
guarantees interoperability between C99's `_Bool' and Fortran's
`C_Bool'-kind logicals and C99 defines that `true' has the value 1 and
`false' the value 0. Using any other integer value with GNU Fortran's
`LOGICAL' (with any kind parameter) gives an undefined result.
(Passing other integer values than 0 and 1 to GCC's `_Bool' is also
undefined, unless the integer is explicitly or implicitly casted to
`_Bool'.)

File: gfortran.info, Node: Derived Types and struct, Next: Interoperable Global Variables, Prev: Intrinsic Types, Up: Interoperability with C
7.1.2 Derived Types and struct
------------------------------
For compatibility of derived types with `struct', one needs to use the
`BIND(C)' attribute in the type declaration. For instance, the
following type declaration
USE ISO_C_BINDING
TYPE, BIND(C) :: myType
INTEGER(C_INT) :: i1, i2
INTEGER(C_SIGNED_CHAR) :: i3
REAL(C_DOUBLE) :: d1
COMPLEX(C_FLOAT_COMPLEX) :: c1
CHARACTER(KIND=C_CHAR) :: str(5)
END TYPE
matches the following `struct' declaration in C
struct {
int i1, i2;
/* Note: "char" might be signed or unsigned. */
signed char i3;
double d1;
float _Complex c1;
char str[5];
} myType;
Derived types with the C binding attribute shall not have the
`sequence' attribute, type parameters, the `extends' attribute, nor
type-bound procedures. Every component must be of interoperable type
and kind and may not have the `pointer' or `allocatable' attribute.
The names of the components are irrelevant for interoperability.
As there exist no direct Fortran equivalents, neither unions nor
structs with bit field or variable-length array members are
interoperable.

File: gfortran.info, Node: Interoperable Global Variables, Next: Interoperable Subroutines and Functions, Prev: Derived Types and struct, Up: Interoperability with C
7.1.3 Interoperable Global Variables
------------------------------------
Variables can be made accessible from C using the C binding attribute,
optionally together with specifying a binding name. Those variables
have to be declared in the declaration part of a `MODULE', be of
interoperable type, and have neither the `pointer' nor the
`allocatable' attribute.
MODULE m
USE myType_module
USE ISO_C_BINDING
integer(C_INT), bind(C, name="_MyProject_flags") :: global_flag
type(myType), bind(C) :: tp
END MODULE
Here, `_MyProject_flags' is the case-sensitive name of the variable
as seen from C programs while `global_flag' is the case-insensitive
name as seen from Fortran. If no binding name is specified, as for TP,
the C binding name is the (lowercase) Fortran binding name. If a
binding name is specified, only a single variable may be after the
double colon. Note of warning: You cannot use a global variable to
access ERRNO of the C library as the C standard allows it to be a
macro. Use the `IERRNO' intrinsic (GNU extension) instead.

File: gfortran.info, Node: Interoperable Subroutines and Functions, Next: Working with Pointers, Prev: Interoperable Global Variables, Up: Interoperability with C
7.1.4 Interoperable Subroutines and Functions
---------------------------------------------
Subroutines and functions have to have the `BIND(C)' attribute to be
compatible with C. The dummy argument declaration is relatively
straightforward. However, one needs to be careful because C uses
call-by-value by default while Fortran behaves usually similar to
call-by-reference. Furthermore, strings and pointers are handled
differently. Note that in Fortran 2003 and 2008 only explicit size and
assumed-size arrays are supported but not assumed-shape or
deferred-shape (i.e. allocatable or pointer) arrays. However, those
are allowed since the Technical Specification 29113, see *note Further
Interoperability of Fortran with C::
To pass a variable by value, use the `VALUE' attribute. Thus, the
following C prototype
`int func(int i, int *j)'
matches the Fortran declaration
integer(c_int) function func(i,j)
use iso_c_binding, only: c_int
integer(c_int), VALUE :: i
integer(c_int) :: j
Note that pointer arguments also frequently need the `VALUE'
attribute, see *note Working with Pointers::.
Strings are handled quite differently in C and Fortran. In C a
string is a `NUL'-terminated array of characters while in Fortran each
string has a length associated with it and is thus not terminated (by
e.g. `NUL'). For example, if one wants to use the following C
function,
#include <stdio.h>
void print_C(char *string) /* equivalent: char string[] */
{
printf("%s\n", string);
}
to print "Hello World" from Fortran, one can call it using
use iso_c_binding, only: C_CHAR, C_NULL_CHAR
interface
subroutine print_c(string) bind(C, name="print_C")
use iso_c_binding, only: c_char
character(kind=c_char) :: string(*)
end subroutine print_c
end interface
call print_c(C_CHAR_"Hello World"//C_NULL_CHAR)
As the example shows, one needs to ensure that the string is `NUL'
terminated. Additionally, the dummy argument STRING of `print_C' is a
length-one assumed-size array; using `character(len=*)' is not allowed.
The example above uses `c_char_"Hello World"' to ensure the string
literal has the right type; typically the default character kind and
`c_char' are the same and thus `"Hello World"' is equivalent. However,
the standard does not guarantee this.
The use of strings is now further illustrated using the C library
function `strncpy', whose prototype is
char *strncpy(char *restrict s1, const char *restrict s2, size_t n);
The function `strncpy' copies at most N characters from string S2 to
S1 and returns S1. In the following example, we ignore the return
value:
use iso_c_binding
implicit none
character(len=30) :: str,str2
interface
! Ignore the return value of strncpy -> subroutine
! "restrict" is always assumed if we do not pass a pointer
subroutine strncpy(dest, src, n) bind(C)
import
character(kind=c_char), intent(out) :: dest(*)
character(kind=c_char), intent(in) :: src(*)
integer(c_size_t), value, intent(in) :: n
end subroutine strncpy
end interface
str = repeat('X',30) ! Initialize whole string with 'X'
call strncpy(str, c_char_"Hello World"//C_NULL_CHAR, &
len(c_char_"Hello World",kind=c_size_t))
print '(a)', str ! prints: "Hello WorldXXXXXXXXXXXXXXXXXXX"
end
The intrinsic procedures are described in *note Intrinsic
Procedures::.

File: gfortran.info, Node: Working with Pointers, Next: Further Interoperability of Fortran with C, Prev: Interoperable Subroutines and Functions, Up: Interoperability with C
7.1.5 Working with Pointers
---------------------------
C pointers are represented in Fortran via the special opaque derived
type `type(c_ptr)' (with private components). Thus one needs to use
intrinsic conversion procedures to convert from or to C pointers.
For some applications, using an assumed type (`TYPE(*)') can be an
alternative to a C pointer; see *note Further Interoperability of
Fortran with C::.
For example,
use iso_c_binding
type(c_ptr) :: cptr1, cptr2
integer, target :: array(7), scalar
integer, pointer :: pa(:), ps
cptr1 = c_loc(array(1)) ! The programmer needs to ensure that the
! array is contiguous if required by the C
! procedure
cptr2 = c_loc(scalar)
call c_f_pointer(cptr2, ps)
call c_f_pointer(cptr2, pa, shape=[7])
When converting C to Fortran arrays, the one-dimensional `SHAPE'
argument has to be passed.
If a pointer is a dummy-argument of an interoperable procedure, it
usually has to be declared using the `VALUE' attribute. `void*'
matches `TYPE(C_PTR), VALUE', while `TYPE(C_PTR)' alone matches
`void**'.
Procedure pointers are handled analogously to pointers; the C type is
`TYPE(C_FUNPTR)' and the intrinsic conversion procedures are
`C_F_PROCPOINTER' and `C_FUNLOC'.
Let us consider two examples of actually passing a procedure pointer
from C to Fortran and vice versa. Note that these examples are also
very similar to passing ordinary pointers between both languages. First,
consider this code in C:
/* Procedure implemented in Fortran. */
void get_values (void (*)(double));
/* Call-back routine we want called from Fortran. */
void
print_it (double x)
{
printf ("Number is %f.\n", x);
}
/* Call Fortran routine and pass call-back to it. */
void
foobar ()
{
get_values (&print_it);
}
A matching implementation for `get_values' in Fortran, that correctly
receives the procedure pointer from C and is able to call it, is given
in the following `MODULE':
MODULE m
IMPLICIT NONE
! Define interface of call-back routine.
ABSTRACT INTERFACE
SUBROUTINE callback (x)
USE, INTRINSIC :: ISO_C_BINDING
REAL(KIND=C_DOUBLE), INTENT(IN), VALUE :: x
END SUBROUTINE callback
END INTERFACE
CONTAINS
! Define C-bound procedure.
SUBROUTINE get_values (cproc) BIND(C)
USE, INTRINSIC :: ISO_C_BINDING
TYPE(C_FUNPTR), INTENT(IN), VALUE :: cproc
PROCEDURE(callback), POINTER :: proc
! Convert C to Fortran procedure pointer.
CALL C_F_PROCPOINTER (cproc, proc)
! Call it.
CALL proc (1.0_C_DOUBLE)
CALL proc (-42.0_C_DOUBLE)
CALL proc (18.12_C_DOUBLE)
END SUBROUTINE get_values
END MODULE m
Next, we want to call a C routine that expects a procedure pointer
argument and pass it a Fortran procedure (which clearly must be
interoperable!). Again, the C function may be:
int
call_it (int (*func)(int), int arg)
{
return func (arg);
}
It can be used as in the following Fortran code:
MODULE m
USE, INTRINSIC :: ISO_C_BINDING
IMPLICIT NONE
! Define interface of C function.
INTERFACE
INTEGER(KIND=C_INT) FUNCTION call_it (func, arg) BIND(C)
USE, INTRINSIC :: ISO_C_BINDING
TYPE(C_FUNPTR), INTENT(IN), VALUE :: func
INTEGER(KIND=C_INT), INTENT(IN), VALUE :: arg
END FUNCTION call_it
END INTERFACE
CONTAINS
! Define procedure passed to C function.
! It must be interoperable!
INTEGER(KIND=C_INT) FUNCTION double_it (arg) BIND(C)
INTEGER(KIND=C_INT), INTENT(IN), VALUE :: arg
double_it = arg + arg
END FUNCTION double_it
! Call C function.
SUBROUTINE foobar ()
TYPE(C_FUNPTR) :: cproc
INTEGER(KIND=C_INT) :: i
! Get C procedure pointer.
cproc = C_FUNLOC (double_it)
! Use it.
DO i = 1_C_INT, 10_C_INT
PRINT *, call_it (cproc, i)
END DO
END SUBROUTINE foobar
END MODULE m

File: gfortran.info, Node: Further Interoperability of Fortran with C, Prev: Working with Pointers, Up: Interoperability with C
7.1.6 Further Interoperability of Fortran with C
------------------------------------------------
The Technical Specification ISO/IEC TS 29113:2012 on further
interoperability of Fortran with C extends the interoperability support
of Fortran 2003 and Fortran 2008. Besides removing some restrictions
and constraints, it adds assumed-type (`TYPE(*)') and assumed-rank
(`dimension') variables and allows for interoperability of
assumed-shape, assumed-rank and deferred-shape arrays, including
allocatables and pointers.
Note: Currently, GNU Fortran does not use internally the array
descriptor (dope vector) as specified in the Technical Specification,
but uses an array descriptor with different fields. Assumed type and
assumed rank formal arguments are converted in the library to the
specified form. The ISO_Fortran_binding API functions (also Fortran
2018 18.4) are implemented in libgfortran. Alternatively, the Chasm
Language Interoperability Tools,
`http://chasm-interop.sourceforge.net/', provide an interface to GNU
Fortran's array descriptor.
The Technical Specification adds the following new features, which
are supported by GNU Fortran:
* The `ASYNCHRONOUS' attribute has been clarified and extended to
allow its use with asynchronous communication in user-provided
libraries such as in implementations of the Message Passing
Interface specification.
* Many constraints have been relaxed, in particular for the `C_LOC'
and `C_F_POINTER' intrinsics.
* The `OPTIONAL' attribute is now allowed for dummy arguments; an
absent argument matches a `NULL' pointer.
* Assumed types (`TYPE(*)') have been added, which may only be used
for dummy arguments. They are unlimited polymorphic but contrary
to `CLASS(*)' they do not contain any type information, similar to
C's `void *' pointers. Expressions of any type and kind can be
passed; thus, it can be used as replacement for `TYPE(C_PTR)',
avoiding the use of `C_LOC' in the caller.
Note, however, that `TYPE(*)' only accepts scalar arguments,
unless the `DIMENSION' is explicitly specified. As `DIMENSION(*)'
only supports array (including array elements) but no scalars, it
is not a full replacement for `C_LOC'. On the other hand,
assumed-type assumed-rank dummy arguments (`TYPE(*),
DIMENSION(..)') allow for both scalars and arrays, but require
special code on the callee side to handle the array descriptor.
* Assumed-rank arrays (`DIMENSION(..)') as dummy argument allow that
scalars and arrays of any rank can be passed as actual argument.
As the Technical Specification does not provide for direct means
to operate with them, they have to be used either from the C side
or be converted using `C_LOC' and `C_F_POINTER' to scalars or
arrays of a specific rank. The rank can be determined using the
`RANK' intrinisic.
Currently unimplemented:
* GNU Fortran always uses an array descriptor, which does not match
the one of the Technical Specification. The
`ISO_Fortran_binding.h' header file and the C functions it
specifies are not available.
* Using assumed-shape, assumed-rank and deferred-shape arrays in
`BIND(C)' procedures is not fully supported. In particular, C
interoperable strings of other length than one are not supported
as this requires the new array descriptor.

File: gfortran.info, Node: GNU Fortran Compiler Directives, Next: Non-Fortran Main Program, Prev: Interoperability with C, Up: Mixed-Language Programming
7.2 GNU Fortran Compiler Directives
===================================
* Menu:
* ATTRIBUTES directive::
* UNROLL directive::
* BUILTIN directive::
* IVDEP directive::
* VECTOR directive::
* NOVECTOR directive::

File: gfortran.info, Node: ATTRIBUTES directive, Next: UNROLL directive, Up: GNU Fortran Compiler Directives
7.2.1 ATTRIBUTES directive
--------------------------
The Fortran standard describes how a conforming program shall behave;
however, the exact implementation is not standardized. In order to
allow the user to choose specific implementation details, compiler
directives can be used to set attributes of variables and procedures
which are not part of the standard. Whether a given attribute is
supported and its exact effects depend on both the operating system and
on the processor; see *note C Extensions: (gcc)Top. for details.
For procedures and procedure pointers, the following attributes can
be used to change the calling convention:
* `CDECL' - standard C calling convention
* `STDCALL' - convention where the called procedure pops the stack
* `FASTCALL' - part of the arguments are passed via registers
instead using the stack
Besides changing the calling convention, the attributes also
influence the decoration of the symbol name, e.g., by a leading
underscore or by a trailing at-sign followed by the number of bytes on
the stack. When assigning a procedure to a procedure pointer, both
should use the same calling convention.
On some systems, procedures and global variables (module variables
and `COMMON' blocks) need special handling to be accessible when they
are in a shared library. The following attributes are available:
* `DLLEXPORT' - provide a global pointer to a pointer in the DLL
* `DLLIMPORT' - reference the function or variable using a global
pointer
For dummy arguments, the `NO_ARG_CHECK' attribute can be used; in
other compilers, it is also known as `IGNORE_TKR'. For dummy arguments
with this attribute actual arguments of any type and kind (similar to
`TYPE(*)'), scalars and arrays of any rank (no equivalent in Fortran
standard) are accepted. As with `TYPE(*)', the argument is unlimited
polymorphic and no type information is available. Additionally, the
argument may only be passed to dummy arguments with the `NO_ARG_CHECK'
attribute and as argument to the `PRESENT' intrinsic function and to
`C_LOC' of the `ISO_C_BINDING' module.
Variables with `NO_ARG_CHECK' attribute shall be of assumed-type
(`TYPE(*)'; recommended) or of type `INTEGER', `LOGICAL', `REAL' or
`COMPLEX'. They shall not have the `ALLOCATE', `CODIMENSION',
`INTENT(OUT)', `POINTER' or `VALUE' attribute; furthermore, they shall
be either scalar or of assumed-size (`dimension(*)'). As `TYPE(*)', the
`NO_ARG_CHECK' attribute requires an explicit interface.
* `NO_ARG_CHECK' - disable the type, kind and rank checking
The attributes are specified using the syntax
`!GCC$ ATTRIBUTES' ATTRIBUTE-LIST `::' VARIABLE-LIST
where in free-form source code only whitespace is allowed before
`!GCC$' and in fixed-form source code `!GCC$', `cGCC$' or `*GCC$' shall
start in the first column.
For procedures, the compiler directives shall be placed into the body
of the procedure; for variables and procedure pointers, they shall be in
the same declaration part as the variable or procedure pointer.

File: gfortran.info, Node: UNROLL directive, Next: BUILTIN directive, Prev: ATTRIBUTES directive, Up: GNU Fortran Compiler Directives
7.2.2 UNROLL directive
----------------------
The syntax of the directive is
`!GCC$ unroll N'
You can use this directive to control how many times a loop should
be unrolled. It must be placed immediately before a `DO' loop and
applies only to the loop that follows. N is an integer constant
specifying the unrolling factor. The values of 0 and 1 block any
unrolling of the loop.

File: gfortran.info, Node: BUILTIN directive, Next: IVDEP directive, Prev: UNROLL directive, Up: GNU Fortran Compiler Directives
7.2.3 BUILTIN directive
-----------------------
The syntax of the directive is
`!GCC$ BUILTIN (B) attributes simd FLAGS IF('target')'
You can use this directive to define which middle-end built-ins
provide vector implementations. `B' is name of the middle-end
built-in. `FLAGS' are optional and must be either "(inbranch)" or
"(notinbranch)". `IF' statement is optional and is used to filter
multilib ABIs for the built-in that should be vectorized. Example
usage:
!GCC$ builtin (sinf) attributes simd (notinbranch) if('x86_64')
The purpose of the directive is to provide an API among the GCC
compiler and the GNU C Library which would define vector
implementations of math routines.

File: gfortran.info, Node: IVDEP directive, Next: VECTOR directive, Prev: BUILTIN directive, Up: GNU Fortran Compiler Directives
7.2.4 IVDEP directive
---------------------
The syntax of the directive is
`!GCC$ ivdep'
This directive tells the compiler to ignore vector dependencies in
the following loop. It must be placed immediately before a `DO' loop
and applies only to the loop that follows.
Sometimes the compiler may not have sufficient information to decide
whether a particular loop is vectorizable due to potential dependencies
between iterations. The purpose of the directive is to tell the
compiler that vectorization is safe.
This directive is intended for annotation of existing code. For new
code it is recommended to consider OpenMP SIMD directives as potential
alternative.

File: gfortran.info, Node: VECTOR directive, Next: NOVECTOR directive, Prev: IVDEP directive, Up: GNU Fortran Compiler Directives
7.2.5 VECTOR directive
----------------------
The syntax of the directive is
`!GCC$ vector'
This directive tells the compiler to vectorize the following loop.
It must be placed immediately before a `DO' loop and applies only to
the loop that follows.

File: gfortran.info, Node: NOVECTOR directive, Prev: VECTOR directive, Up: GNU Fortran Compiler Directives
7.2.6 NOVECTOR directive
------------------------
The syntax of the directive is
`!GCC$ novector'
This directive tells the compiler to not vectorize the following
loop. It must be placed immediately before a `DO' loop and applies only
to the loop that follows.

File: gfortran.info, Node: Non-Fortran Main Program, Next: Naming and argument-passing conventions, Prev: GNU Fortran Compiler Directives, Up: Mixed-Language Programming
7.3 Non-Fortran Main Program
============================
* Menu:
* _gfortran_set_args:: Save command-line arguments
* _gfortran_set_options:: Set library option flags
* _gfortran_set_convert:: Set endian conversion
* _gfortran_set_record_marker:: Set length of record markers
* _gfortran_set_fpe:: Set when a Floating Point Exception should be raised
* _gfortran_set_max_subrecord_length:: Set subrecord length
Even if you are doing mixed-language programming, it is very likely
that you do not need to know or use the information in this section.
Since it is about the internal structure of GNU Fortran, it may also
change in GCC minor releases.
When you compile a `PROGRAM' with GNU Fortran, a function with the
name `main' (in the symbol table of the object file) is generated,
which initializes the libgfortran library and then calls the actual
program which uses the name `MAIN__', for historic reasons. If you
link GNU Fortran compiled procedures to, e.g., a C or C++ program or to
a Fortran program compiled by a different compiler, the libgfortran
library is not initialized and thus a few intrinsic procedures do not
work properly, e.g. those for obtaining the command-line arguments.
Therefore, if your `PROGRAM' is not compiled with GNU Fortran and
the GNU Fortran compiled procedures require intrinsics relying on the
library initialization, you need to initialize the library yourself.
Using the default options, gfortran calls `_gfortran_set_args' and
`_gfortran_set_options'. The initialization of the former is needed if
the called procedures access the command line (and for backtracing);
the latter sets some flags based on the standard chosen or to enable
backtracing. In typical programs, it is not necessary to call any
initialization function.
If your `PROGRAM' is compiled with GNU Fortran, you shall not call
any of the following functions. The libgfortran initialization
functions are shown in C syntax but using C bindings they are also
accessible from Fortran.

File: gfortran.info, Node: _gfortran_set_args, Next: _gfortran_set_options, Up: Non-Fortran Main Program
7.3.1 `_gfortran_set_args' -- Save command-line arguments
---------------------------------------------------------
_Description_:
`_gfortran_set_args' saves the command-line arguments; this
initialization is required if any of the command-line intrinsics
is called. Additionally, it shall be called if backtracing is
enabled (see `_gfortran_set_options').
_Syntax_:
`void _gfortran_set_args (int argc, char *argv[])'
_Arguments_:
ARGC number of command line argument strings
ARGV the command-line argument strings; argv[0] is
the pathname of the executable itself.
_Example_:
int main (int argc, char *argv[])
{
/* Initialize libgfortran. */
_gfortran_set_args (argc, argv);
return 0;
}

File: gfortran.info, Node: _gfortran_set_options, Next: _gfortran_set_convert, Prev: _gfortran_set_args, Up: Non-Fortran Main Program
7.3.2 `_gfortran_set_options' -- Set library option flags
---------------------------------------------------------
_Description_:
`_gfortran_set_options' sets several flags related to the Fortran
standard to be used, whether backtracing should be enabled and
whether range checks should be performed. The syntax allows for
upward compatibility since the number of passed flags is
specified; for non-passed flags, the default value is used. See
also *note Code Gen Options::. Please note that not all flags are
actually used.
_Syntax_:
`void _gfortran_set_options (int num, int options[])'
_Arguments_:
NUM number of options passed
ARGV The list of flag values
_option flag list_:
OPTION[0] Allowed standard; can give run-time errors if
e.g. an input-output edit descriptor is
invalid in a given standard. Possible values
are (bitwise or-ed) `GFC_STD_F77' (1),
`GFC_STD_F95_OBS' (2), `GFC_STD_F95_DEL' (4),
`GFC_STD_F95' (8), `GFC_STD_F2003' (16),
`GFC_STD_GNU' (32), `GFC_STD_LEGACY' (64),
`GFC_STD_F2008' (128), `GFC_STD_F2008_OBS'
(256), `GFC_STD_F2008_TS' (512),
`GFC_STD_F2018' (1024), `GFC_STD_F2018_OBS'
(2048), and `GFC_STD=F2018_DEL' (4096).
Default: `GFC_STD_F95_OBS | GFC_STD_F95_DEL |
GFC_STD_F95 | GFC_STD_F2003 | GFC_STD_F2008 |
GFC_STD_F2008_TS | GFC_STD_F2008_OBS |
GFC_STD_F77 | GFC_STD_F2018 |
GFC_STD_F2018_OBS | GFC_STD_F2018_DEL |
GFC_STD_GNU | GFC_STD_LEGACY'.
OPTION[1] Standard-warning flag; prints a warning to
standard error. Default: `GFC_STD_F95_DEL |
GFC_STD_LEGACY'.
OPTION[2] If non zero, enable pedantic checking.
Default: off.
OPTION[3] Unused.
OPTION[4] If non zero, enable backtracing on run-time
errors. Default: off. (Default in the
compiler: on.) Note: Installs a signal
handler and requires command-line
initialization using `_gfortran_set_args'.
OPTION[5] If non zero, supports signed zeros. Default:
enabled.
OPTION[6] Enables run-time checking. Possible values
are (bitwise or-ed): GFC_RTCHECK_BOUNDS (1),
GFC_RTCHECK_ARRAY_TEMPS (2),
GFC_RTCHECK_RECURSION (4), GFC_RTCHECK_DO
(16), GFC_RTCHECK_POINTER (32). Default:
disabled.
OPTION[7] Unused.
OPTION[8] Show a warning when invoking `STOP' and `ERROR
STOP' if a floating-point exception occurred.
Possible values are (bitwise or-ed)
`GFC_FPE_INVALID' (1), `GFC_FPE_DENORMAL' (2),
`GFC_FPE_ZERO' (4), `GFC_FPE_OVERFLOW' (8),
`GFC_FPE_UNDERFLOW' (16), `GFC_FPE_INEXACT'
(32). Default: None (0). (Default in the
compiler: `GFC_FPE_INVALID | GFC_FPE_DENORMAL |
GFC_FPE_ZERO | GFC_FPE_OVERFLOW |
GFC_FPE_UNDERFLOW'.)
_Example_:
/* Use gfortran 4.9 default options. */
static int options[] = {68, 511, 0, 0, 1, 1, 0, 0, 31};
_gfortran_set_options (9, &options);

File: gfortran.info, Node: _gfortran_set_convert, Next: _gfortran_set_record_marker, Prev: _gfortran_set_options, Up: Non-Fortran Main Program
7.3.3 `_gfortran_set_convert' -- Set endian conversion
------------------------------------------------------
_Description_:
`_gfortran_set_convert' set the representation of data for
unformatted files.
_Syntax_:
`void _gfortran_set_convert (int conv)'
_Arguments_:
CONV Endian conversion, possible values:
GFC_CONVERT_NATIVE (0, default),
GFC_CONVERT_SWAP (1), GFC_CONVERT_BIG (2),
GFC_CONVERT_LITTLE (3).
_Example_:
int main (int argc, char *argv[])
{
/* Initialize libgfortran. */
_gfortran_set_args (argc, argv);
_gfortran_set_convert (1);
return 0;
}

File: gfortran.info, Node: _gfortran_set_record_marker, Next: _gfortran_set_fpe, Prev: _gfortran_set_convert, Up: Non-Fortran Main Program
7.3.4 `_gfortran_set_record_marker' -- Set length of record markers
-------------------------------------------------------------------
_Description_:
`_gfortran_set_record_marker' sets the length of record markers
for unformatted files.
_Syntax_:
`void _gfortran_set_record_marker (int val)'
_Arguments_:
VAL Length of the record marker; valid values are
4 and 8. Default is 4.
_Example_:
int main (int argc, char *argv[])
{
/* Initialize libgfortran. */
_gfortran_set_args (argc, argv);
_gfortran_set_record_marker (8);
return 0;
}

File: gfortran.info, Node: _gfortran_set_fpe, Next: _gfortran_set_max_subrecord_length, Prev: _gfortran_set_record_marker, Up: Non-Fortran Main Program
7.3.5 `_gfortran_set_fpe' -- Enable floating point exception traps
------------------------------------------------------------------
_Description_:
`_gfortran_set_fpe' enables floating point exception traps for the
specified exceptions. On most systems, this will result in a
SIGFPE signal being sent and the program being aborted.
_Syntax_:
`void _gfortran_set_fpe (int val)'
_Arguments_:
OPTION[0] IEEE exceptions. Possible values are (bitwise
or-ed) zero (0, default) no trapping,
`GFC_FPE_INVALID' (1), `GFC_FPE_DENORMAL' (2),
`GFC_FPE_ZERO' (4), `GFC_FPE_OVERFLOW' (8),
`GFC_FPE_UNDERFLOW' (16), and
`GFC_FPE_INEXACT' (32).
_Example_:
int main (int argc, char *argv[])
{
/* Initialize libgfortran. */
_gfortran_set_args (argc, argv);
/* FPE for invalid operations such as SQRT(-1.0). */
_gfortran_set_fpe (1);
return 0;
}

File: gfortran.info, Node: _gfortran_set_max_subrecord_length, Prev: _gfortran_set_fpe, Up: Non-Fortran Main Program
7.3.6 `_gfortran_set_max_subrecord_length' -- Set subrecord length
------------------------------------------------------------------
_Description_:
`_gfortran_set_max_subrecord_length' set the maximum length for a
subrecord. This option only makes sense for testing and debugging
of unformatted I/O.
_Syntax_:
`void _gfortran_set_max_subrecord_length (int val)'
_Arguments_:
VAL the maximum length for a subrecord; the
maximum permitted value is 2147483639, which
is also the default.
_Example_:
int main (int argc, char *argv[])
{
/* Initialize libgfortran. */
_gfortran_set_args (argc, argv);
_gfortran_set_max_subrecord_length (8);
return 0;
}

File: gfortran.info, Node: Naming and argument-passing conventions, Prev: Non-Fortran Main Program, Up: Mixed-Language Programming
7.4 Naming and argument-passing conventions
===========================================
This section gives an overview about the naming convention of procedures
and global variables and about the argument passing conventions used by
GNU Fortran. If a C binding has been specified, the naming convention
and some of the argument-passing conventions change. If possible,
mixed-language and mixed-compiler projects should use the better defined
C binding for interoperability. See *note Interoperability with C::.
* Menu:
* Naming conventions::
* Argument passing conventions::

File: gfortran.info, Node: Naming conventions, Next: Argument passing conventions, Up: Naming and argument-passing conventions
7.4.1 Naming conventions
------------------------
According the Fortran standard, valid Fortran names consist of a letter
between `A' to `Z', `a' to `z', digits `0', `1' to `9' and underscores
(`_') with the restriction that names may only start with a letter. As
vendor extension, the dollar sign (`$') is additionally permitted with
the option `-fdollar-ok', but not as first character and only if the
target system supports it.
By default, the procedure name is the lower-cased Fortran name with
an appended underscore (`_'); using `-fno-underscoring' no underscore
is appended while `-fsecond-underscore' appends two underscores.
Depending on the target system and the calling convention, the
procedure might be additionally dressed; for instance, on 32bit Windows
with `stdcall', an at-sign `@' followed by an integer number is
appended. For the changing the calling convention, see *note GNU
Fortran Compiler Directives::.
For common blocks, the same convention is used, i.e. by default an
underscore is appended to the lower-cased Fortran name. Blank commons
have the name `__BLNK__'.
For procedures and variables declared in the specification space of a
module, the name is formed by `__', followed by the lower-cased module
name, `_MOD_', and the lower-cased Fortran name. Note that no
underscore is appended.

File: gfortran.info, Node: Argument passing conventions, Prev: Naming conventions, Up: Naming and argument-passing conventions
7.4.2 Argument passing conventions
----------------------------------
Subroutines do not return a value (matching C99's `void') while
functions either return a value as specified in the platform ABI or the
result variable is passed as hidden argument to the function and no
result is returned. A hidden result variable is used when the result
variable is an array or of type `CHARACTER'.
Arguments are passed according to the platform ABI. In particular,
complex arguments might not be compatible to a struct with two real
components for the real and imaginary part. The argument passing
matches the one of C99's `_Complex'. Functions with scalar complex
result variables return their value and do not use a by-reference
argument. Note that with the `-ff2c' option, the argument passing is
modified and no longer completely matches the platform ABI. Some other
Fortran compilers use `f2c' semantic by default; this might cause
problems with interoperablility.
GNU Fortran passes most arguments by reference, i.e. by passing a
pointer to the data. Note that the compiler might use a temporary
variable into which the actual argument has been copied, if required
semantically (copy-in/copy-out).
For arguments with `ALLOCATABLE' and `POINTER' attribute (including
procedure pointers), a pointer to the pointer is passed such that the
pointer address can be modified in the procedure.
For dummy arguments with the `VALUE' attribute: Scalar arguments of
the type `INTEGER', `LOGICAL', `REAL' and `COMPLEX' are passed by value
according to the platform ABI. (As vendor extension and not
recommended, using `%VAL()' in the call to a procedure has the same
effect.) For `TYPE(C_PTR)' and procedure pointers, the pointer itself
is passed such that it can be modified without affecting the caller.
For Boolean (`LOGICAL') arguments, please note that GCC expects only
the integer value 0 and 1. If a GNU Fortran `LOGICAL' variable
contains another integer value, the result is undefined. As some other
Fortran compilers use -1 for `.TRUE.', extra care has to be taken -
such as passing the value as `INTEGER'. (The same value restriction
also applies to other front ends of GCC, e.g. to GCC's C99 compiler for
`_Bool' or GCC's Ada compiler for `Boolean'.)
For arguments of `CHARACTER' type, the character length is passed as
a hidden argument at the end of the argument list. For deferred-length
strings, the value is passed by reference, otherwise by value. The
character length has the C type `size_t' (or `INTEGER(kind=C_SIZE_T)'
in Fortran). Note that this is different to older versions of the GNU
Fortran compiler, where the type of the hidden character length
argument was a C `int'. In order to retain compatibility with older
versions, one can e.g. for the following Fortran procedure
subroutine fstrlen (s, a)
character(len=*) :: s
integer :: a
print*, len(s)
end subroutine fstrlen
define the corresponding C prototype as follows:
#if __GNUC__ > 7
typedef size_t fortran_charlen_t;
#else
typedef int fortran_charlen_t;
#endif
void fstrlen_ (char*, int*, fortran_charlen_t);
In order to avoid such compiler-specific details, for new code it is
instead recommended to use the ISO_C_BINDING feature.
Note with C binding, `CHARACTER(len=1)' result variables are
returned according to the platform ABI and no hidden length argument is
used for dummy arguments; with `VALUE', those variables are passed by
value.
For `OPTIONAL' dummy arguments, an absent argument is denoted by a
NULL pointer, except for scalar dummy arguments of type `INTEGER',
`LOGICAL', `REAL' and `COMPLEX' which have the `VALUE' attribute. For
those, a hidden Boolean argument (`logical(kind=C_bool),value') is used
to indicate whether the argument is present.
Arguments which are assumed-shape, assumed-rank or deferred-rank
arrays or, with `-fcoarray=lib', allocatable scalar coarrays use an
array descriptor. All other arrays pass the address of the first
element of the array. With `-fcoarray=lib', the token and the offset
belonging to nonallocatable coarrays dummy arguments are passed as
hidden argument along the character length hidden arguments. The token
is an oparque pointer identifying the coarray and the offset is a
passed-by-value integer of kind `C_PTRDIFF_T', denoting the byte offset
between the base address of the coarray and the passed scalar or first
element of the passed array.
The arguments are passed in the following order
* Result variable, when the function result is passed by reference
* Character length of the function result, if it is a of type
`CHARACTER' and no C binding is used
* The arguments in the order in which they appear in the Fortran
declaration
* The the present status for optional arguments with value attribute,
which are internally passed by value
* The character length and/or coarray token and offset for the first
argument which is a `CHARACTER' or a nonallocatable coarray dummy
argument, followed by the hidden arguments of the next dummy
argument of such a type

File: gfortran.info, Node: Coarray Programming, Next: Intrinsic Procedures, Prev: Mixed-Language Programming, Up: Top
8 Coarray Programming
*********************
* Menu:
* Type and enum ABI Documentation::
* Function ABI Documentation::

File: gfortran.info, Node: Type and enum ABI Documentation, Next: Function ABI Documentation, Up: Coarray Programming
8.1 Type and enum ABI Documentation
===================================
* Menu:
* caf_token_t::
* caf_register_t::
* caf_deregister_t::
* caf_reference_t::
* caf_team_t::

File: gfortran.info, Node: caf_token_t, Next: caf_register_t, Up: Type and enum ABI Documentation
8.1.1 `caf_token_t'
-------------------
Typedef of type `void *' on the compiler side. Can be any data type on
the library side.

File: gfortran.info, Node: caf_register_t, Next: caf_deregister_t, Prev: caf_token_t, Up: Type and enum ABI Documentation
8.1.2 `caf_register_t'
----------------------
Indicates which kind of coarray variable should be registered.
typedef enum caf_register_t {
CAF_REGTYPE_COARRAY_STATIC,
CAF_REGTYPE_COARRAY_ALLOC,
CAF_REGTYPE_LOCK_STATIC,
CAF_REGTYPE_LOCK_ALLOC,
CAF_REGTYPE_CRITICAL,
CAF_REGTYPE_EVENT_STATIC,
CAF_REGTYPE_EVENT_ALLOC,
CAF_REGTYPE_COARRAY_ALLOC_REGISTER_ONLY,
CAF_REGTYPE_COARRAY_ALLOC_ALLOCATE_ONLY
}
caf_register_t;
The values `CAF_REGTYPE_COARRAY_ALLOC_REGISTER_ONLY' and
`CAF_REGTYPE_COARRAY_ALLOC_ALLOCATE_ONLY' are for allocatable components
in derived type coarrays only. The first one sets up the token without
allocating memory for allocatable component. The latter one only
allocates the memory for an allocatable component in a derived type
coarray. The token needs to be setup previously by the REGISTER_ONLY.
This allows to have allocatable components un-allocated on some images.
The status whether an allocatable component is allocated on a remote
image can be queried by `_caf_is_present' which used internally by the
`ALLOCATED' intrinsic.

File: gfortran.info, Node: caf_deregister_t, Next: caf_reference_t, Prev: caf_register_t, Up: Type and enum ABI Documentation
8.1.3 `caf_deregister_t'
------------------------
typedef enum caf_deregister_t {
CAF_DEREGTYPE_COARRAY_DEREGISTER,
CAF_DEREGTYPE_COARRAY_DEALLOCATE_ONLY
}
caf_deregister_t;
Allows to specifiy the type of deregistration of a coarray object. The
`CAF_DEREGTYPE_COARRAY_DEALLOCATE_ONLY' flag is only allowed for
allocatable components in derived type coarrays.

File: gfortran.info, Node: caf_reference_t, Next: caf_team_t, Prev: caf_deregister_t, Up: Type and enum ABI Documentation
8.1.4 `caf_reference_t'
-----------------------
The structure used for implementing arbitrary reference chains. A
`CAF_REFERENCE_T' allows to specify a component reference or any kind
of array reference of any rank supported by gfortran. For array
references all kinds as known by the compiler/Fortran standard are
supported indicated by a `MODE'.
typedef enum caf_ref_type_t {
/* Reference a component of a derived type, either regular one or an
allocatable or pointer type. For regular ones idx in caf_reference_t is
set to -1. */
CAF_REF_COMPONENT,
/* Reference an allocatable array. */
CAF_REF_ARRAY,
/* Reference a non-allocatable/non-pointer array. I.e., the coarray object
has no array descriptor associated and the addressing is done
completely using the ref. */
CAF_REF_STATIC_ARRAY
} caf_ref_type_t;
typedef enum caf_array_ref_t {
/* No array ref. This terminates the array ref. */
CAF_ARR_REF_NONE = 0,
/* Reference array elements given by a vector. Only for this mode
caf_reference_t.u.a.dim[i].v is valid. */
CAF_ARR_REF_VECTOR,
/* A full array ref (:). */
CAF_ARR_REF_FULL,
/* Reference a range on elements given by start, end and stride. */
CAF_ARR_REF_RANGE,
/* Only a single item is referenced given in the start member. */
CAF_ARR_REF_SINGLE,
/* An array ref of the kind (i:), where i is an arbitrary valid index in the
array. The index i is given in the start member. */
CAF_ARR_REF_OPEN_END,
/* An array ref of the kind (:i), where the lower bound of the array ref
is given by the remote side. The index i is given in the end member. */
CAF_ARR_REF_OPEN_START
} caf_array_ref_t;
/* References to remote components of a derived type. */
typedef struct caf_reference_t {
/* A pointer to the next ref or NULL. */
struct caf_reference_t *next;
/* The type of the reference. */
/* caf_ref_type_t, replaced by int to allow specification in fortran FE. */
int type;
/* The size of an item referenced in bytes. I.e. in an array ref this is
the factor to advance the array pointer with to get to the next item.
For component refs this gives just the size of the element referenced. */
size_t item_size;
union {
struct {
/* The offset (in bytes) of the component in the derived type.
Unused for allocatable or pointer components. */
ptrdiff_t offset;
/* The offset (in bytes) to the caf_token associated with this
component. NULL, when not allocatable/pointer ref. */
ptrdiff_t caf_token_offset;
} c;
struct {
/* The mode of the array ref. See CAF_ARR_REF_*. */
/* caf_array_ref_t, replaced by unsigend char to allow specification in
fortran FE. */
unsigned char mode[GFC_MAX_DIMENSIONS];
/* The type of a static array. Unset for array's with descriptors. */
int static_array_type;
/* Subscript refs (s) or vector refs (v). */
union {
struct {
/* The start and end boundary of the ref and the stride. */
index_type start, end, stride;
} s;
struct {
/* nvec entries of kind giving the elements to reference. */
void *vector;
/* The number of entries in vector. */
size_t nvec;
/* The integer kind used for the elements in vector. */
int kind;
} v;
} dim[GFC_MAX_DIMENSIONS];
} a;
} u;
} caf_reference_t;
The references make up a single linked list of reference operations.
The `NEXT' member links to the next reference or NULL to indicate the
end of the chain. Component and array refs can be arbitrarly mixed as
long as they comply to the Fortran standard.
_NOTES_ The member `STATIC_ARRAY_TYPE' is used only when the `TYPE'
is `CAF_REF_STATIC_ARRAY'. The member gives the type of the data
referenced. Because no array descriptor is available for a
descriptor-less array and type conversion still needs to take place the
type is transported here.
At the moment `CAF_ARR_REF_VECTOR' is not implemented in the front
end for descriptor-less arrays. The library caf_single has untested
support for it.

File: gfortran.info, Node: caf_team_t, Prev: caf_reference_t, Up: Type and enum ABI Documentation
8.1.5 `caf_team_t'
------------------
Opaque pointer to represent a team-handle. This type is a stand-in for
the future implementation of teams. It is about to change without
further notice.

File: gfortran.info, Node: Function ABI Documentation, Prev: Type and enum ABI Documentation, Up: Coarray Programming
8.2 Function ABI Documentation
==============================
* Menu:
* _gfortran_caf_init:: Initialiation function
* _gfortran_caf_finish:: Finalization function
* _gfortran_caf_this_image:: Querying the image number
* _gfortran_caf_num_images:: Querying the maximal number of images
* _gfortran_caf_image_status :: Query the status of an image
* _gfortran_caf_failed_images :: Get an array of the indexes of the failed images
* _gfortran_caf_stopped_images :: Get an array of the indexes of the stopped images
* _gfortran_caf_register:: Registering coarrays
* _gfortran_caf_deregister:: Deregistering coarrays
* _gfortran_caf_is_present:: Query whether an allocatable or pointer component in a derived type coarray is allocated
* _gfortran_caf_send:: Sending data from a local image to a remote image
* _gfortran_caf_get:: Getting data from a remote image
* _gfortran_caf_sendget:: Sending data between remote images
* _gfortran_caf_send_by_ref:: Sending data from a local image to a remote image using enhanced references
* _gfortran_caf_get_by_ref:: Getting data from a remote image using enhanced references
* _gfortran_caf_sendget_by_ref:: Sending data between remote images using enhanced references
* _gfortran_caf_lock:: Locking a lock variable
* _gfortran_caf_unlock:: Unlocking a lock variable
* _gfortran_caf_event_post:: Post an event
* _gfortran_caf_event_wait:: Wait that an event occurred
* _gfortran_caf_event_query:: Query event count
* _gfortran_caf_sync_all:: All-image barrier
* _gfortran_caf_sync_images:: Barrier for selected images
* _gfortran_caf_sync_memory:: Wait for completion of segment-memory operations
* _gfortran_caf_error_stop:: Error termination with exit code
* _gfortran_caf_error_stop_str:: Error termination with string
* _gfortran_caf_fail_image :: Mark the image failed and end its execution
* _gfortran_caf_atomic_define:: Atomic variable assignment
* _gfortran_caf_atomic_ref:: Atomic variable reference
* _gfortran_caf_atomic_cas:: Atomic compare and swap
* _gfortran_caf_atomic_op:: Atomic operation
* _gfortran_caf_co_broadcast:: Sending data to all images
* _gfortran_caf_co_max:: Collective maximum reduction
* _gfortran_caf_co_min:: Collective minimum reduction
* _gfortran_caf_co_sum:: Collective summing reduction
* _gfortran_caf_co_reduce:: Generic collective reduction

File: gfortran.info, Node: _gfortran_caf_init, Next: _gfortran_caf_finish, Up: Function ABI Documentation
8.2.1 `_gfortran_caf_init' -- Initialiation function
----------------------------------------------------
_Description_:
This function is called at startup of the program before the
Fortran main program, if the latter has been compiled with
`-fcoarray=lib'. It takes as arguments the command-line arguments
of the program. It is permitted to pass two `NULL' pointers as
argument; if non-`NULL', the library is permitted to modify the
arguments.
_Syntax_:
`void _gfortran_caf_init (int *argc, char ***argv)'
_Arguments_:
ARGC intent(inout) An integer pointer with the
number of arguments passed to the program or
`NULL'.
ARGV intent(inout) A pointer to an array of strings
with the command-line arguments or `NULL'.
_NOTES_
The function is modelled after the initialization function of the
Message Passing Interface (MPI) specification. Due to the way
coarray registration works, it might not be the first call to the
library. If the main program is not written in Fortran and only a
library uses coarrays, it can happen that this function is never
called. Therefore, it is recommended that the library does not
rely on the passed arguments and whether the call has been done.

File: gfortran.info, Node: _gfortran_caf_finish, Next: _gfortran_caf_this_image, Prev: _gfortran_caf_init, Up: Function ABI Documentation
8.2.2 `_gfortran_caf_finish' -- Finalization function
-----------------------------------------------------
_Description_:
This function is called at the end of the Fortran main program, if
it has been compiled with the `-fcoarray=lib' option.
_Syntax_:
`void _gfortran_caf_finish (void)'
_NOTES_
For non-Fortran programs, it is recommended to call the function
at the end of the main program. To ensure that the shutdown is
also performed for programs where this function is not explicitly
invoked, for instance non-Fortran programs or calls to the
system's exit() function, the library can use a destructor
function. Note that programs can also be terminated using the
STOP and ERROR STOP statements; those use different library calls.

File: gfortran.info, Node: _gfortran_caf_this_image, Next: _gfortran_caf_num_images, Prev: _gfortran_caf_finish, Up: Function ABI Documentation
8.2.3 `_gfortran_caf_this_image' -- Querying the image number
-------------------------------------------------------------
_Description_:
This function returns the current image number, which is a
positive number.
_Syntax_:
`int _gfortran_caf_this_image (int distance)'
_Arguments_:
DISTANCE As specified for the `this_image' intrinsic in
TS18508. Shall be a non-negative number.
_NOTES_
If the Fortran intrinsic `this_image' is invoked without an
argument, which is the only permitted form in Fortran 2008, GCC
passes `0' as first argument.

File: gfortran.info, Node: _gfortran_caf_num_images, Next: _gfortran_caf_image_status, Prev: _gfortran_caf_this_image, Up: Function ABI Documentation
8.2.4 `_gfortran_caf_num_images' -- Querying the maximal number of images
-------------------------------------------------------------------------
_Description_:
This function returns the number of images in the current team, if
DISTANCE is 0 or the number of images in the parent team at the
specified distance. If failed is -1, the function returns the
number of all images at the specified distance; if it is 0, the
function returns the number of nonfailed images, and if it is 1,
it returns the number of failed images.
_Syntax_:
`int _gfortran_caf_num_images(int distance, int failed)'
_Arguments_:
DISTANCE the distance from this image to the ancestor.
Shall be positive.
FAILED shall be -1, 0, or 1
_NOTES_
This function follows TS18508. If the num_image intrinsic has no
arguments, then the compiler passes `distance=0' and `failed=-1'
to the function.

File: gfortran.info, Node: _gfortran_caf_image_status, Next: _gfortran_caf_failed_images, Prev: _gfortran_caf_num_images, Up: Function ABI Documentation
8.2.5 `_gfortran_caf_image_status' -- Query the status of an image
------------------------------------------------------------------
_Description_:
Get the status of the image given by the id IMAGE of the team
given by TEAM. Valid results are zero, for image is ok,
`STAT_STOPPED_IMAGE' from the ISO_FORTRAN_ENV module to indicate
that the image has been stopped and `STAT_FAILED_IMAGE' also from
ISO_FORTRAN_ENV to indicate that the image has executed a `FAIL
IMAGE' statement.
_Syntax_:
`int _gfortran_caf_image_status (int image, caf_team_t * team)'
_Arguments_:
IMAGE the positive scalar id of the image in the
current TEAM.
TEAM optional; team on the which the inquiry is to
be performed.
_NOTES_
This function follows TS18508. Because team-functionality is not
yet implemented a null-pointer is passed for the TEAM argument at
the moment.

File: gfortran.info, Node: _gfortran_caf_failed_images, Next: _gfortran_caf_stopped_images, Prev: _gfortran_caf_image_status, Up: Function ABI Documentation
8.2.6 `_gfortran_caf_failed_images' -- Get an array of the indexes of the failed images
---------------------------------------------------------------------------------------
_Description_:
Get an array of image indexes in the current TEAM that have
failed. The array is sorted ascendingly. When TEAM is not
provided the current team is to be used. When KIND is provided
then the resulting array is of that integer kind else it is of
default integer kind. The returns an unallocated size zero array
when no images have failed.
_Syntax_:
`int _gfortran_caf_failed_images (caf_team_t * team, int * kind)'
_Arguments_:
TEAM optional; team on the which the inquiry is to
be performed.
IMAGE optional; the kind of the resulting integer
array.
_NOTES_
This function follows TS18508. Because team-functionality is not
yet implemented a null-pointer is passed for the TEAM argument at
the moment.

File: gfortran.info, Node: _gfortran_caf_stopped_images, Next: _gfortran_caf_register, Prev: _gfortran_caf_failed_images, Up: Function ABI Documentation
8.2.7 `_gfortran_caf_stopped_images' -- Get an array of the indexes of the stopped images
-----------------------------------------------------------------------------------------
_Description_:
Get an array of image indexes in the current TEAM that have
stopped. The array is sorted ascendingly. When TEAM is not
provided the current team is to be used. When KIND is provided
then the resulting array is of that integer kind else it is of
default integer kind. The returns an unallocated size zero array
when no images have failed.
_Syntax_:
`int _gfortran_caf_stopped_images (caf_team_t * team, int * kind)'
_Arguments_:
TEAM optional; team on the which the inquiry is to
be performed.
IMAGE optional; the kind of the resulting integer
array.
_NOTES_
This function follows TS18508. Because team-functionality is not
yet implemented a null-pointer is passed for the TEAM argument at
the moment.

File: gfortran.info, Node: _gfortran_caf_register, Next: _gfortran_caf_deregister, Prev: _gfortran_caf_stopped_images, Up: Function ABI Documentation
8.2.8 `_gfortran_caf_register' -- Registering coarrays
------------------------------------------------------
_Description_:
Registers memory for a coarray and creates a token to identify the
coarray. The routine is called for both coarrays with `SAVE'
attribute and using an explicit `ALLOCATE' statement. If an error
occurs and STAT is a `NULL' pointer, the function shall abort with
printing an error message and starting the error termination. If
no error occurs and STAT is present, it shall be set to zero.
Otherwise, it shall be set to a positive value and, if not-`NULL',
ERRMSG shall be set to a string describing the failure. The
routine shall register the memory provided in the `DATA'-component
of the array descriptor DESC, when that component is non-`NULL',
else it shall allocate sufficient memory and provide a pointer to
it in the `DATA'-component of DESC. The array descriptor has rank
zero, when a scalar object is to be registered and the array
descriptor may be invalid after the call to
`_gfortran_caf_register'. When an array is to be allocated the
descriptor persists.
For `CAF_REGTYPE_COARRAY_STATIC' and `CAF_REGTYPE_COARRAY_ALLOC',
the passed size is the byte size requested. For
`CAF_REGTYPE_LOCK_STATIC', `CAF_REGTYPE_LOCK_ALLOC' and
`CAF_REGTYPE_CRITICAL' it is the array size or one for a scalar.
When `CAF_REGTYPE_COARRAY_ALLOC_REGISTER_ONLY' is used, then only
a token for an allocatable or pointer component is created. The
`SIZE' parameter is not used then. On the contrary when
`CAF_REGTYPE_COARRAY_ALLOC_ALLOCATE_ONLY' is specified, then the
TOKEN needs to be registered by a previous call with regtype
`CAF_REGTYPE_COARRAY_ALLOC_REGISTER_ONLY' and either the memory
specified in the DESC's data-ptr is registered or allocate when
the data-ptr is `NULL'.
_Syntax_:
`void caf_register (size_t size, caf_register_t type, caf_token_t
*token, gfc_descriptor_t *desc, int *stat, char *errmsg, size_t
errmsg_len)'
_Arguments_:
SIZE For normal coarrays, the byte size of the
coarray to be allocated; for lock types and
event types, the number of elements.
TYPE one of the caf_register_t types.
TOKEN intent(out) An opaque pointer identifying the
coarray.
DESC intent(inout) The (pseudo) array descriptor.
STAT intent(out) For allocatable coarrays, stores
the STAT=; may be `NULL'
ERRMSG intent(out) When an error occurs, this will be
set to an error message; may be `NULL'
ERRMSG_LEN the buffer size of errmsg.
_NOTES_
Nonallocatable coarrays have to be registered prior use from
remote images. In order to guarantee this, they have to be
registered before the main program. This can be achieved by
creating constructor functions. That is what GCC does such that
also for nonallocatable coarrays the memory is allocated and no
static memory is used. The token permits to identify the coarray;
to the processor, the token is a nonaliasing pointer. The library
can, for instance, store the base address of the coarray in the
token, some handle or a more complicated struct. The library may
also store the array descriptor DESC when its rank is non-zero.
For lock types, the value shall only be used for checking the
allocation status. Note that for critical blocks, the locking is
only required on one image; in the locking statement, the
processor shall always pass an image index of one for
critical-block lock variables (`CAF_REGTYPE_CRITICAL'). For lock
types and critical-block variables, the initial value shall be
unlocked (or, respecitively, not in critical section) such as the
value false; for event types, the initial state should be no
event, e.g. zero.

File: gfortran.info, Node: _gfortran_caf_deregister, Next: _gfortran_caf_is_present, Prev: _gfortran_caf_register, Up: Function ABI Documentation
8.2.9 `_gfortran_caf_deregister' -- Deregistering coarrays
----------------------------------------------------------
_Description_:
Called to free or deregister the memory of a coarray; the
processor calls this function for automatic and explicit
deallocation. In case of an error, this function shall fail with
an error message, unless the STAT variable is not null. The
library is only expected to free memory it allocated itself during
a call to `_gfortran_caf_register'.
_Syntax_:
`void caf_deregister (caf_token_t *token, caf_deregister_t type,
int *stat, char *errmsg, size_t errmsg_len)'
_Arguments_:
TOKEN the token to free.
TYPE the type of action to take for the coarray. A
`CAF_DEREGTYPE_COARRAY_DEALLOCATE_ONLY' is
allowed only for allocatable or pointer
components of derived type coarrays. The
action only deallocates the local memory
without deleting the token.
STAT intent(out) Stores the STAT=; may be NULL
ERRMSG intent(out) When an error occurs, this will be
set to an error message; may be NULL
ERRMSG_LEN the buffer size of errmsg.
_NOTES_
For nonalloatable coarrays this function is never called. If a
cleanup is required, it has to be handled via the finish, stop and
error stop functions, and via destructors.

File: gfortran.info, Node: _gfortran_caf_is_present, Next: _gfortran_caf_send, Prev: _gfortran_caf_deregister, Up: Function ABI Documentation
8.2.10 `_gfortran_caf_is_present' -- Query whether an allocatable or pointer component in a derived type coarray is allocated
-----------------------------------------------------------------------------------------------------------------------------
_Description_:
Used to query the coarray library whether an allocatable component
in a derived type coarray is allocated on a remote image.
_Syntax_:
`void _gfortran_caf_is_present (caf_token_t token, int image_index,
gfc_reference_t *ref)'
_Arguments_:
TOKEN An opaque pointer identifying the coarray.
IMAGE_INDEXThe ID of the remote image; must be a positive
number.
REF A chain of references to address the
allocatable or pointer component in the
derived type coarray. The object reference
needs to be a scalar or a full array
reference, respectively.

File: gfortran.info, Node: _gfortran_caf_send, Next: _gfortran_caf_get, Prev: _gfortran_caf_is_present, Up: Function ABI Documentation
8.2.11 `_gfortran_caf_send' -- Sending data from a local image to a remote image
--------------------------------------------------------------------------------
_Description_:
Called to send a scalar, an array section or a whole array from a
local to a remote image identified by the image_index.
_Syntax_:
`void _gfortran_caf_send (caf_token_t token, size_t offset, int
image_index, gfc_descriptor_t *dest, caf_vector_t *dst_vector,
gfc_descriptor_t *src, int dst_kind, int src_kind, bool
may_require_tmp, int *stat)'
_Arguments_:
TOKEN intent(in) An opaque pointer identifying the
coarray.
OFFSET intent(in) By which amount of bytes the
actual data is shifted compared to the base
address of the coarray.
IMAGE_INDEXintent(in) The ID of the remote image; must
be a positive number.
DEST intent(in) Array descriptor for the remote
image for the bounds and the size. The
`base_addr' shall not be accessed.
DST_VECTOR intent(in) If not NULL, it contains the vector
subscript of the destination array; the values
are relative to the dimension triplet of the
dest argument.
SRC intent(in) Array descriptor of the local
array to be transferred to the remote image
DST_KIND intent(in) Kind of the destination argument
SRC_KIND intent(in) Kind of the source argument
MAY_REQUIRE_TMPintent(in) The variable is `false' when it is
known at compile time that the DEST and SRC
either cannot overlap or overlap (fully or
partially) such that walking SRC and DEST in
element wise element order (honoring the
stride value) will not lead to wrong results.
Otherwise, the value is `true'.
STAT intent(out) when non-NULL give the result of
the operation, i.e., zero on success and
non-zero on error. When NULL and an error
occurs, then an error message is printed and
the program is terminated.
_NOTES_
It is permitted to have IMAGE_INDEX equal the current image; the
memory of the send-to and the send-from might (partially) overlap
in that case. The implementation has to take care that it handles
this case, e.g. using `memmove' which handles (partially)
overlapping memory. If MAY_REQUIRE_TMP is true, the library might
additionally create a temporary variable, unless additional checks
show that this is not required (e.g. because walking backward is
possible or because both arrays are contiguous and `memmove' takes
care of overlap issues).
Note that the assignment of a scalar to an array is permitted. In
addition, the library has to handle numeric-type conversion and
for strings, padding and different character kinds.

File: gfortran.info, Node: _gfortran_caf_get, Next: _gfortran_caf_sendget, Prev: _gfortran_caf_send, Up: Function ABI Documentation
8.2.12 `_gfortran_caf_get' -- Getting data from a remote image
--------------------------------------------------------------
_Description_:
Called to get an array section or a whole array from a remote,
image identified by the image_index.
_Syntax_:
`void _gfortran_caf_get (caf_token_t token, size_t offset, int
image_index, gfc_descriptor_t *src, caf_vector_t *src_vector,
gfc_descriptor_t *dest, int src_kind, int dst_kind, bool
may_require_tmp, int *stat)'
_Arguments_:
TOKEN intent(in) An opaque pointer identifying the
coarray.
OFFSET intent(in) By which amount of bytes the
actual data is shifted compared to the base
address of the coarray.
IMAGE_INDEXintent(in) The ID of the remote image; must
be a positive number.
DEST intent(out) Array descriptor of the local
array to store the data retrieved from the
remote image
SRC intent(in) Array descriptor for the remote
image for the bounds and the size. The
`base_addr' shall not be accessed.
SRC_VECTOR intent(in) If not NULL, it contains the vector
subscript of the source array; the values are
relative to the dimension triplet of the SRC
argument.
DST_KIND intent(in) Kind of the destination argument
SRC_KIND intent(in) Kind of the source argument
MAY_REQUIRE_TMPintent(in) The variable is `false' when it is
known at compile time that the DEST and SRC
either cannot overlap or overlap (fully or
partially) such that walking SRC and DEST in
element wise element order (honoring the
stride value) will not lead to wrong results.
Otherwise, the value is `true'.
STAT intent(out) When non-NULL give the result of
the operation, i.e., zero on success and
non-zero on error. When NULL and an error
occurs, then an error message is printed and
the program is terminated.
_NOTES_
It is permitted to have IMAGE_INDEX equal the current image; the
memory of the send-to and the send-from might (partially) overlap
in that case. The implementation has to take care that it handles
this case, e.g. using `memmove' which handles (partially)
overlapping memory. If MAY_REQUIRE_TMP is true, the library might
additionally create a temporary variable, unless additional checks
show that this is not required (e.g. because walking backward is
possible or because both arrays are contiguous and `memmove' takes
care of overlap issues).
Note that the library has to handle numeric-type conversion and
for strings, padding and different character kinds.

File: gfortran.info, Node: _gfortran_caf_sendget, Next: _gfortran_caf_send_by_ref, Prev: _gfortran_caf_get, Up: Function ABI Documentation
8.2.13 `_gfortran_caf_sendget' -- Sending data between remote images
--------------------------------------------------------------------
_Description_:
Called to send a scalar, an array section or a whole array from a
remote image identified by the SRC_IMAGE_INDEX to a remote image
identified by the DST_IMAGE_INDEX.
_Syntax_:
`void _gfortran_caf_sendget (caf_token_t dst_token, size_t
dst_offset, int dst_image_index, gfc_descriptor_t *dest,
caf_vector_t *dst_vector, caf_token_t src_token, size_t
src_offset, int src_image_index, gfc_descriptor_t *src,
caf_vector_t *src_vector, int dst_kind, int src_kind, bool
may_require_tmp, int *stat)'
_Arguments_:
DST_TOKEN intent(in) An opaque pointer identifying the
destination coarray.
DST_OFFSET intent(in) By which amount of bytes the
actual data is shifted compared to the base
address of the destination coarray.
DST_IMAGE_INDEXintent(in) The ID of the destination remote
image; must be a positive number.
DEST intent(in) Array descriptor for the destination
remote image for the bounds and the size. The
`base_addr' shall not be accessed.
DST_VECTOR intent(int) If not NULL, it contains the
vector subscript of the destination array; the
values are relative to the dimension triplet
of the DEST argument.
SRC_TOKEN intent(in) An opaque pointer identifying the
source coarray.
SRC_OFFSET intent(in) By which amount of bytes the
actual data is shifted compared to the base
address of the source coarray.
SRC_IMAGE_INDEXintent(in) The ID of the source remote image;
must be a positive number.
SRC intent(in) Array descriptor of the local array
to be transferred to the remote image.
SRC_VECTOR intent(in) Array descriptor of the local array
to be transferred to the remote image
DST_KIND intent(in) Kind of the destination argument
SRC_KIND intent(in) Kind of the source argument
MAY_REQUIRE_TMPintent(in) The variable is `false' when it is
known at compile time that the DEST and SRC
either cannot overlap or overlap (fully or
partially) such that walking SRC and DEST in
element wise element order (honoring the
stride value) will not lead to wrong results.
Otherwise, the value is `true'.
STAT intent(out) when non-NULL give the result of
the operation, i.e., zero on success and
non-zero on error. When NULL and an error
occurs, then an error message is printed and
the program is terminated.
_NOTES_
It is permitted to have the same image index for both
SRC_IMAGE_INDEX and DST_IMAGE_INDEX; the memory of the send-to and
the send-from might (partially) overlap in that case. The
implementation has to take care that it handles this case, e.g.
using `memmove' which handles (partially) overlapping memory. If
MAY_REQUIRE_TMP is true, the library might additionally create a
temporary variable, unless additional checks show that this is not
required (e.g. because walking backward is possible or because
both arrays are contiguous and `memmove' takes care of overlap
issues).
Note that the assignment of a scalar to an array is permitted. In
addition, the library has to handle numeric-type conversion and
for strings, padding and different character kinds.

File: gfortran.info, Node: _gfortran_caf_send_by_ref, Next: _gfortran_caf_get_by_ref, Prev: _gfortran_caf_sendget, Up: Function ABI Documentation
8.2.14 `_gfortran_caf_send_by_ref' -- Sending data from a local image to a remote image with enhanced referencing options
-------------------------------------------------------------------------------------------------------------------------
_Description_:
Called to send a scalar, an array section or a whole array from a
local to a remote image identified by the IMAGE_INDEX.
_Syntax_:
`void _gfortran_caf_send_by_ref (caf_token_t token, int
image_index, gfc_descriptor_t *src, caf_reference_t *refs, int
dst_kind, int src_kind, bool may_require_tmp, bool
dst_reallocatable, int *stat, int dst_type)'
_Arguments_:
TOKEN intent(in) An opaque pointer identifying the
coarray.
IMAGE_INDEXintent(in) The ID of the remote image; must
be a positive number.
SRC intent(in) Array descriptor of the local array
to be transferred to the remote image
REFS intent(in) The references on the remote array
to store the data given by src. Guaranteed to
have at least one entry.
DST_KIND intent(in) Kind of the destination argument
SRC_KIND intent(in) Kind of the source argument
MAY_REQUIRE_TMPintent(in) The variable is `false' when it is
known at compile time that the DEST and SRC
either cannot overlap or overlap (fully or
partially) such that walking SRC and DEST in
element wise element order (honoring the
stride value) will not lead to wrong results.
Otherwise, the value is `true'.
DST_REALLOCATABLEintent(in) Set when the destination is of
allocatable or pointer type and the refs will
allow reallocation, i.e., the ref is a full
array or component ref.
STAT intent(out) When non-`NULL' give the result of
the operation, i.e., zero on success and
non-zero on error. When `NULL' and an error
occurs, then an error message is printed and
the program is terminated.
DST_TYPE intent(in) Give the type of the destination.
When the destination is not an array, than the
precise type, e.g. of a component in a derived
type, is not known, but provided here.
_NOTES_
It is permitted to have IMAGE_INDEX equal the current image; the
memory of the send-to and the send-from might (partially) overlap
in that case. The implementation has to take care that it handles
this case, e.g. using `memmove' which handles (partially)
overlapping memory. If MAY_REQUIRE_TMP is true, the library might
additionally create a temporary variable, unless additional checks
show that this is not required (e.g. because walking backward is
possible or because both arrays are contiguous and `memmove' takes
care of overlap issues).
Note that the assignment of a scalar to an array is permitted. In
addition, the library has to handle numeric-type conversion and
for strings, padding and different character kinds.
Because of the more complicated references possible some
operations may be unsupported by certain libraries. The library
is expected to issue a precise error message why the operation is
not permitted.

File: gfortran.info, Node: _gfortran_caf_get_by_ref, Next: _gfortran_caf_sendget_by_ref, Prev: _gfortran_caf_send_by_ref, Up: Function ABI Documentation
8.2.15 `_gfortran_caf_get_by_ref' -- Getting data from a remote image using enhanced references
-----------------------------------------------------------------------------------------------
_Description_:
Called to get a scalar, an array section or a whole array from a
remote image identified by the IMAGE_INDEX.
_Syntax_:
`void _gfortran_caf_get_by_ref (caf_token_t token, int image_index,
caf_reference_t *refs, gfc_descriptor_t *dst, int dst_kind, int
src_kind, bool may_require_tmp, bool dst_reallocatable, int *stat,
int src_type)'
_Arguments_:
TOKEN intent(in) An opaque pointer identifying the
coarray.
IMAGE_INDEXintent(in) The ID of the remote image; must
be a positive number.
REFS intent(in) The references to apply to the
remote structure to get the data.
DST intent(in) Array descriptor of the local array
to store the data transferred from the remote
image. May be reallocated where needed and
when DST_REALLOCATABLE allows it.
DST_KIND intent(in) Kind of the destination argument
SRC_KIND intent(in) Kind of the source argument
MAY_REQUIRE_TMPintent(in) The variable is `false' when it is
known at compile time that the DEST and SRC
either cannot overlap or overlap (fully or
partially) such that walking SRC and DEST in
element wise element order (honoring the
stride value) will not lead to wrong results.
Otherwise, the value is `true'.
DST_REALLOCATABLEintent(in) Set when DST is of allocatable or
pointer type and its refs allow reallocation,
i.e., the full array or a component is
referenced.
STAT intent(out) When non-`NULL' give the result of
the operation, i.e., zero on success and
non-zero on error. When `NULL' and an error
occurs, then an error message is printed and
the program is terminated.
SRC_TYPE intent(in) Give the type of the source. When
the source is not an array, than the precise
type, e.g. of a component in a derived type,
is not known, but provided here.
_NOTES_
It is permitted to have `image_index' equal the current image; the
memory of the send-to and the send-from might (partially) overlap
in that case. The implementation has to take care that it handles
this case, e.g. using `memmove' which handles (partially)
overlapping memory. If MAY_REQUIRE_TMP is true, the library might
additionally create a temporary variable, unless additional checks
show that this is not required (e.g. because walking backward is
possible or because both arrays are contiguous and `memmove' takes
care of overlap issues).
Note that the library has to handle numeric-type conversion and
for strings, padding and different character kinds.
Because of the more complicated references possible some
operations may be unsupported by certain libraries. The library
is expected to issue a precise error message why the operation is
not permitted.

File: gfortran.info, Node: _gfortran_caf_sendget_by_ref, Next: _gfortran_caf_lock, Prev: _gfortran_caf_get_by_ref, Up: Function ABI Documentation
8.2.16 `_gfortran_caf_sendget_by_ref' -- Sending data between remote images using enhanced references on both sides
-------------------------------------------------------------------------------------------------------------------
_Description_:
Called to send a scalar, an array section or a whole array from a
remote image identified by the SRC_IMAGE_INDEX to a remote image
identified by the DST_IMAGE_INDEX.
_Syntax_:
`void _gfortran_caf_sendget_by_ref (caf_token_t dst_token, int
dst_image_index, caf_reference_t *dst_refs, caf_token_t src_token,
int src_image_index, caf_reference_t *src_refs, int dst_kind, int
src_kind, bool may_require_tmp, int *dst_stat, int *src_stat, int
dst_type, int src_type)'
_Arguments_:
DST_TOKEN intent(in) An opaque pointer identifying the
destination coarray.
DST_IMAGE_INDEXintent(in) The ID of the destination remote
image; must be a positive number.
DST_REFS intent(in) The references on the remote array
to store the data given by the source.
Guaranteed to have at least one entry.
SRC_TOKEN intent(in) An opaque pointer identifying the
source coarray.
SRC_IMAGE_INDEXintent(in) The ID of the source remote image;
must be a positive number.
SRC_REFS intent(in) The references to apply to the
remote structure to get the data.
DST_KIND intent(in) Kind of the destination argument
SRC_KIND intent(in) Kind of the source argument
MAY_REQUIRE_TMPintent(in) The variable is `false' when it is
known at compile time that the DEST and SRC
either cannot overlap or overlap (fully or
partially) such that walking SRC and DEST in
element wise element order (honoring the
stride value) will not lead to wrong results.
Otherwise, the value is `true'.
DST_STAT intent(out) when non-`NULL' give the result of
the send-operation, i.e., zero on success and
non-zero on error. When `NULL' and an error
occurs, then an error message is printed and
the program is terminated.
SRC_STAT intent(out) When non-`NULL' give the result of
the get-operation, i.e., zero on success and
non-zero on error. When `NULL' and an error
occurs, then an error message is printed and
the program is terminated.
DST_TYPE intent(in) Give the type of the destination.
When the destination is not an array, than the
precise type, e.g. of a component in a derived
type, is not known, but provided here.
SRC_TYPE intent(in) Give the type of the source. When
the source is not an array, than the precise
type, e.g. of a component in a derived type,
is not known, but provided here.
_NOTES_
It is permitted to have the same image index for both
SRC_IMAGE_INDEX and DST_IMAGE_INDEX; the memory of the send-to and
the send-from might (partially) overlap in that case. The
implementation has to take care that it handles this case, e.g.
using `memmove' which handles (partially) overlapping memory. If
MAY_REQUIRE_TMP is true, the library might additionally create a
temporary variable, unless additional checks show that this is not
required (e.g. because walking backward is possible or because
both arrays are contiguous and `memmove' takes care of overlap
issues).
Note that the assignment of a scalar to an array is permitted. In
addition, the library has to handle numeric-type conversion and
for strings, padding and different character kinds.
Because of the more complicated references possible some
operations may be unsupported by certain libraries. The library
is expected to issue a precise error message why the operation is
not permitted.

File: gfortran.info, Node: _gfortran_caf_lock, Next: _gfortran_caf_unlock, Prev: _gfortran_caf_sendget_by_ref, Up: Function ABI Documentation
8.2.17 `_gfortran_caf_lock' -- Locking a lock variable
------------------------------------------------------
_Description_:
Acquire a lock on the given image on a scalar locking variable or
for the given array element for an array-valued variable. If the
AQUIRED_LOCK is `NULL', the function returns after having obtained
the lock. If it is non-`NULL', then ACQUIRED_LOCK is assigned the
value true (one) when the lock could be obtained and false (zero)
otherwise. Locking a lock variable which has already been locked
by the same image is an error.
_Syntax_:
`void _gfortran_caf_lock (caf_token_t token, size_t index, int
image_index, int *aquired_lock, int *stat, char *errmsg, size_t
errmsg_len)'
_Arguments_:
TOKEN intent(in) An opaque pointer identifying the
coarray.
INDEX intent(in) Array index; first array index is
0. For scalars, it is always 0.
IMAGE_INDEXintent(in) The ID of the remote image; must
be a positive number.
AQUIRED_LOCKintent(out) If not NULL, it returns whether
lock could be obtained.
STAT intent(out) Stores the STAT=; may be NULL.
ERRMSG intent(out) When an error occurs, this will be
set to an error message; may be NULL.
ERRMSG_LEN intent(in) the buffer size of errmsg
_NOTES_
This function is also called for critical blocks; for those, the
array index is always zero and the image index is one. Libraries
are permitted to use other images for critical-block locking
variables.

File: gfortran.info, Node: _gfortran_caf_unlock, Next: _gfortran_caf_event_post, Prev: _gfortran_caf_lock, Up: Function ABI Documentation
8.2.18 `_gfortran_caf_lock' -- Unlocking a lock variable
--------------------------------------------------------
_Description_:
Release a lock on the given image on a scalar locking variable or
for the given array element for an array-valued variable.
Unlocking a lock variable which is unlocked or has been locked by
a different image is an error.
_Syntax_:
`void _gfortran_caf_unlock (caf_token_t token, size_t index, int
image_index, int *stat, char *errmsg, size_t errmsg_len)'
_Arguments_:
TOKEN intent(in) An opaque pointer identifying the
coarray.
INDEX intent(in) Array index; first array index is
0. For scalars, it is always 0.
IMAGE_INDEXintent(in) The ID of the remote image; must
be a positive number.
STAT intent(out) For allocatable coarrays, stores
the STAT=; may be NULL.
ERRMSG intent(out) When an error occurs, this will be
set to an error message; may be NULL.
ERRMSG_LEN intent(in) the buffer size of errmsg
_NOTES_
This function is also called for critical block; for those, the
array index is always zero and the image index is one. Libraries
are permitted to use other images for critical-block locking
variables.

File: gfortran.info, Node: _gfortran_caf_event_post, Next: _gfortran_caf_event_wait, Prev: _gfortran_caf_unlock, Up: Function ABI Documentation
8.2.19 `_gfortran_caf_event_post' -- Post an event
--------------------------------------------------
_Description_:
Increment the event count of the specified event variable.
_Syntax_:
`void _gfortran_caf_event_post (caf_token_t token, size_t index,
int image_index, int *stat, char *errmsg, size_t errmsg_len)'
_Arguments_:
TOKEN intent(in) An opaque pointer identifying the
coarray.
INDEX intent(in) Array index; first array index is
0. For scalars, it is always 0.
IMAGE_INDEXintent(in) The ID of the remote image; must
be a positive number; zero indicates the
current image, when accessed noncoindexed.
STAT intent(out) Stores the STAT=; may be NULL.
ERRMSG intent(out) When an error occurs, this will
be set to an error message; may be NULL.
ERRMSG_LEN intent(in) the buffer size of errmsg
_NOTES_
This acts like an atomic add of one to the remote image's event
variable. The statement is an image-control statement but does
not imply sync memory. Still, all preceeding push communications
of this image to the specified remote image have to be completed
before `event_wait' on the remote image returns.

File: gfortran.info, Node: _gfortran_caf_event_wait, Next: _gfortran_caf_event_query, Prev: _gfortran_caf_event_post, Up: Function ABI Documentation
8.2.20 `_gfortran_caf_event_wait' -- Wait that an event occurred
----------------------------------------------------------------
_Description_:
Wait until the event count has reached at least the specified
UNTIL_COUNT; if so, atomically decrement the event variable by this
amount and return.
_Syntax_:
`void _gfortran_caf_event_wait (caf_token_t token, size_t index,
int until_count, int *stat, char *errmsg, size_t errmsg_len)'
_Arguments_:
TOKEN intent(in) An opaque pointer identifying the
coarray.
INDEX intent(in) Array index; first array index is
0. For scalars, it is always 0.
UNTIL_COUNTintent(in) The number of events which have to
be available before the function returns.
STAT intent(out) Stores the STAT=; may be NULL.
ERRMSG intent(out) When an error occurs, this will
be set to an error message; may be NULL.
ERRMSG_LEN intent(in) the buffer size of errmsg
_NOTES_
This function only operates on a local coarray. It acts like a
loop checking atomically the value of the event variable, breaking
if the value is greater or equal the requested number of counts.
Before the function returns, the event variable has to be
decremented by the requested UNTIL_COUNT value. A possible
implementation would be a busy loop for a certain number of spins
(possibly depending on the number of threads relative to the
number of available cores) followed by another waiting strategy
such as a sleeping wait (possibly with an increasing number of
sleep time) or, if possible, a futex wait.
The statement is an image-control statement but does not imply
sync memory. Still, all preceeding push communications of this
image to the specified remote image have to be completed before
`event_wait' on the remote image returns.

File: gfortran.info, Node: _gfortran_caf_event_query, Next: _gfortran_caf_sync_all, Prev: _gfortran_caf_event_wait, Up: Function ABI Documentation
8.2.21 `_gfortran_caf_event_query' -- Query event count
-------------------------------------------------------
_Description_:
Return the event count of the specified event variable.
_Syntax_:
`void _gfortran_caf_event_query (caf_token_t token, size_t index,
int image_index, int *count, int *stat)'
_Arguments_:
TOKEN intent(in) An opaque pointer identifying the
coarray.
INDEX intent(in) Array index; first array index is
0. For scalars, it is always 0.
IMAGE_INDEXintent(in) The ID of the remote image; must
be a positive number; zero indicates the
current image when accessed noncoindexed.
COUNT intent(out) The number of events currently
posted to the event variable.
STAT intent(out) Stores the STAT=; may be NULL.
_NOTES_
The typical use is to check the local event variable to only call
`event_wait' when the data is available. However, a coindexed
variable is permitted; there is no ordering or synchronization
implied. It acts like an atomic fetch of the value of the event
variable.

File: gfortran.info, Node: _gfortran_caf_sync_all, Next: _gfortran_caf_sync_images, Prev: _gfortran_caf_event_query, Up: Function ABI Documentation
8.2.22 `_gfortran_caf_sync_all' -- All-image barrier
----------------------------------------------------
_Description_:
Synchronization of all images in the current team; the program
only continues on a given image after this function has been
called on all images of the current team. Additionally, it
ensures that all pending data transfers of previous segment have
completed.
_Syntax_:
`void _gfortran_caf_sync_all (int *stat, char *errmsg, size_t
errmsg_len)'
_Arguments_:
STAT intent(out) Stores the status STAT= and may
be NULL.
ERRMSG intent(out) When an error occurs, this will
be set to an error message; may be NULL.
ERRMSG_LEN intent(in) the buffer size of errmsg

File: gfortran.info, Node: _gfortran_caf_sync_images, Next: _gfortran_caf_sync_memory, Prev: _gfortran_caf_sync_all, Up: Function ABI Documentation
8.2.23 `_gfortran_caf_sync_images' -- Barrier for selected images
-----------------------------------------------------------------
_Description_:
Synchronization between the specified images; the program only
continues on a given image after this function has been called on
all images specified for that image. Note that one image can wait
for all other images in the current team (e.g. via `sync
images(*)') while those only wait for that specific image.
Additionally, `sync images' ensures that all pending data
transfers of previous segments have completed.
_Syntax_:
`void _gfortran_caf_sync_images (int count, int images[], int
*stat, char *errmsg, size_t errmsg_len)'
_Arguments_:
COUNT intent(in) The number of images which are
provided in the next argument. For a
zero-sized array, the value is zero. For
`sync images (*)', the value is -1.
IMAGES intent(in) An array with the images provided
by the user. If COUNT is zero, a NULL pointer
is passed.
STAT intent(out) Stores the status STAT= and may
be NULL.
ERRMSG intent(out) When an error occurs, this will
be set to an error message; may be NULL.
ERRMSG_LEN intent(in) the buffer size of errmsg

File: gfortran.info, Node: _gfortran_caf_sync_memory, Next: _gfortran_caf_error_stop, Prev: _gfortran_caf_sync_images, Up: Function ABI Documentation
8.2.24 `_gfortran_caf_sync_memory' -- Wait for completion of segment-memory operations
--------------------------------------------------------------------------------------
_Description_:
Acts as optimization barrier between different segments. It also
ensures that all pending memory operations of this image have been
completed.
_Syntax_:
`void _gfortran_caf_sync_memory (int *stat, char *errmsg, size_t
errmsg_len)'
_Arguments_:
STAT intent(out) Stores the status STAT= and may
be NULL.
ERRMSG intent(out) When an error occurs, this will
be set to an error message; may be NULL.
ERRMSG_LEN intent(in) the buffer size of errmsg
_NOTE_ A simple implementation could be
`__asm__ __volatile__ ("":::"memory")' to prevent code movements.

File: gfortran.info, Node: _gfortran_caf_error_stop, Next: _gfortran_caf_error_stop_str, Prev: _gfortran_caf_sync_memory, Up: Function ABI Documentation
8.2.25 `_gfortran_caf_error_stop' -- Error termination with exit code
---------------------------------------------------------------------
_Description_:
Invoked for an `ERROR STOP' statement which has an integer
argument. The function should terminate the program with the
specified exit code.
_Syntax_:
`void _gfortran_caf_error_stop (int error)'
_Arguments_:
ERROR intent(in) The exit status to be used.

File: gfortran.info, Node: _gfortran_caf_error_stop_str, Next: _gfortran_caf_fail_image, Prev: _gfortran_caf_error_stop, Up: Function ABI Documentation
8.2.26 `_gfortran_caf_error_stop_str' -- Error termination with string
----------------------------------------------------------------------
_Description_:
Invoked for an `ERROR STOP' statement which has a string as
argument. The function should terminate the program with a
nonzero-exit code.
_Syntax_:
`void _gfortran_caf_error_stop (const char *string, size_t len)'
_Arguments_:
STRING intent(in) the error message (not zero
terminated)
LEN intent(in) the length of the string

File: gfortran.info, Node: _gfortran_caf_fail_image, Next: _gfortran_caf_atomic_define, Prev: _gfortran_caf_error_stop_str, Up: Function ABI Documentation
8.2.27 `_gfortran_caf_fail_image' -- Mark the image failed and end its execution
--------------------------------------------------------------------------------
_Description_:
Invoked for an `FAIL IMAGE' statement. The function should
terminate the current image.
_Syntax_:
`void _gfortran_caf_fail_image ()'
_NOTES_
This function follows TS18508.

File: gfortran.info, Node: _gfortran_caf_atomic_define, Next: _gfortran_caf_atomic_ref, Prev: _gfortran_caf_fail_image, Up: Function ABI Documentation
8.2.28 `_gfortran_caf_atomic_define' -- Atomic variable assignment
------------------------------------------------------------------
_Description_:
Assign atomically a value to an integer or logical variable.
_Syntax_:
`void _gfortran_caf_atomic_define (caf_token_t token, size_t
offset, int image_index, void *value, int *stat, int type, int
kind)'
_Arguments_:
TOKEN intent(in) An opaque pointer identifying the
coarray.
OFFSET intent(in) By which amount of bytes the
actual data is shifted compared to the base
address of the coarray.
IMAGE_INDEXintent(in) The ID of the remote image; must
be a positive number; zero indicates the
current image when used noncoindexed.
VALUE intent(in) the value to be assigned, passed
by reference
STAT intent(out) Stores the status STAT= and may
be NULL.
TYPE intent(in) The data type, i.e. `BT_INTEGER'
(1) or `BT_LOGICAL' (2).
KIND intent(in) The kind value (only 4; always
`int')

File: gfortran.info, Node: _gfortran_caf_atomic_ref, Next: _gfortran_caf_atomic_cas, Prev: _gfortran_caf_atomic_define, Up: Function ABI Documentation
8.2.29 `_gfortran_caf_atomic_ref' -- Atomic variable reference
--------------------------------------------------------------
_Description_:
Reference atomically a value of a kind-4 integer or logical
variable.
_Syntax_:
`void _gfortran_caf_atomic_ref (caf_token_t token, size_t offset,
int image_index, void *value, int *stat, int type, int kind)'
_Arguments_:
TOKEN intent(in) An opaque pointer identifying the
coarray.
OFFSET intent(in) By which amount of bytes the
actual data is shifted compared to the base
address of the coarray.
IMAGE_INDEXintent(in) The ID of the remote image; must
be a positive number; zero indicates the
current image when used noncoindexed.
VALUE intent(out) The variable assigned the
atomically referenced variable.
STAT intent(out) Stores the status STAT= and may be
NULL.
TYPE the data type, i.e. `BT_INTEGER' (1) or
`BT_LOGICAL' (2).
KIND The kind value (only 4; always `int')

File: gfortran.info, Node: _gfortran_caf_atomic_cas, Next: _gfortran_caf_atomic_op, Prev: _gfortran_caf_atomic_ref, Up: Function ABI Documentation
8.2.30 `_gfortran_caf_atomic_cas' -- Atomic compare and swap
------------------------------------------------------------
_Description_:
Atomic compare and swap of a kind-4 integer or logical variable.
Assigns atomically the specified value to the atomic variable, if
the latter has the value specified by the passed condition value.
_Syntax_:
`void _gfortran_caf_atomic_cas (caf_token_t token, size_t offset,
int image_index, void *old, void *compare, void *new_val, int
*stat, int type, int kind)'
_Arguments_:
TOKEN intent(in) An opaque pointer identifying the
coarray.
OFFSET intent(in) By which amount of bytes the
actual data is shifted compared to the base
address of the coarray.
IMAGE_INDEXintent(in) The ID of the remote image; must
be a positive number; zero indicates the
current image when used noncoindexed.
OLD intent(out) The value which the atomic
variable had just before the cas operation.
COMPARE intent(in) The value used for comparision.
NEW_VAL intent(in) The new value for the atomic
variable, assigned to the atomic variable, if
`compare' equals the value of the atomic
variable.
STAT intent(out) Stores the status STAT= and may
be NULL.
TYPE intent(in) the data type, i.e. `BT_INTEGER'
(1) or `BT_LOGICAL' (2).
KIND intent(in) The kind value (only 4; always
`int')

File: gfortran.info, Node: _gfortran_caf_atomic_op, Next: _gfortran_caf_co_broadcast, Prev: _gfortran_caf_atomic_cas, Up: Function ABI Documentation
8.2.31 `_gfortran_caf_atomic_op' -- Atomic operation
----------------------------------------------------
_Description_:
Apply an operation atomically to an atomic integer or logical
variable. After the operation, OLD contains the value just before
the operation, which, respectively, adds (GFC_CAF_ATOMIC_ADD)
atomically the `value' to the atomic integer variable or does a
bitwise AND, OR or exclusive OR between the atomic variable and
VALUE; the result is then stored in the atomic variable.
_Syntax_:
`void _gfortran_caf_atomic_op (int op, caf_token_t token, size_t
offset, int image_index, void *value, void *old, int *stat, int
type, int kind)'
_Arguments_:
OP intent(in) the operation to be performed;
possible values `GFC_CAF_ATOMIC_ADD' (1),
`GFC_CAF_ATOMIC_AND' (2), `GFC_CAF_ATOMIC_OR'
(3), `GFC_CAF_ATOMIC_XOR' (4).
TOKEN intent(in) An opaque pointer identifying the
coarray.
OFFSET intent(in) By which amount of bytes the
actual data is shifted compared to the base
address of the coarray.
IMAGE_INDEXintent(in) The ID of the remote image; must
be a positive number; zero indicates the
current image when used noncoindexed.
OLD intent(out) The value which the atomic
variable had just before the atomic operation.
VAL intent(in) The new value for the atomic
variable, assigned to the atomic variable, if
`compare' equals the value of the atomic
variable.
STAT intent(out) Stores the status STAT= and may
be NULL.
TYPE intent(in) the data type, i.e. `BT_INTEGER'
(1) or `BT_LOGICAL' (2)
KIND intent(in) the kind value (only 4; always
`int')

File: gfortran.info, Node: _gfortran_caf_co_broadcast, Next: _gfortran_caf_co_max, Prev: _gfortran_caf_atomic_op, Up: Function ABI Documentation
8.2.32 `_gfortran_caf_co_broadcast' -- Sending data to all images
-----------------------------------------------------------------
_Description_:
Distribute a value from a given image to all other images in the
team. Has to be called collectively.
_Syntax_:
`void _gfortran_caf_co_broadcast (gfc_descriptor_t *a, int
source_image, int *stat, char *errmsg, size_t errmsg_len)'
_Arguments_:
A intent(inout) An array descriptor with the
data to be broadcasted (on SOURCE_IMAGE) or to
be received (other images).
SOURCE_IMAGEintent(in) The ID of the image from which the
data should be broadcasted.
STAT intent(out) Stores the status STAT= and may
be NULL.
ERRMSG intent(out) When an error occurs, this will
be set to an error message; may be NULL.
ERRMSG_LEN intent(in) the buffer size of errmsg.

File: gfortran.info, Node: _gfortran_caf_co_max, Next: _gfortran_caf_co_min, Prev: _gfortran_caf_co_broadcast, Up: Function ABI Documentation
8.2.33 `_gfortran_caf_co_max' -- Collective maximum reduction
-------------------------------------------------------------
_Description_:
Calculates for each array element of the variable A the maximum
value for that element in the current team; if RESULT_IMAGE has the
value 0, the result shall be stored on all images, otherwise, only
on the specified image. This function operates on numeric values
and character strings.
_Syntax_:
`void _gfortran_caf_co_max (gfc_descriptor_t *a, int result_image,
int *stat, char *errmsg, int a_len, size_t errmsg_len)'
_Arguments_:
A intent(inout) An array descriptor for the
data to be processed. On the destination
image(s) the result overwrites the old content.
RESULT_IMAGEintent(in) The ID of the image to which the
reduced value should be copied to; if zero, it
has to be copied to all images.
STAT intent(out) Stores the status STAT= and may
be NULL.
ERRMSG intent(out) When an error occurs, this will
be set to an error message; may be NULL.
A_LEN intent(in) the string length of argument A
ERRMSG_LEN intent(in) the buffer size of errmsg
_NOTES_
If RESULT_IMAGE is nonzero, the data in the array descriptor A on
all images except of the specified one become undefined; hence,
the library may make use of this.

File: gfortran.info, Node: _gfortran_caf_co_min, Next: _gfortran_caf_co_sum, Prev: _gfortran_caf_co_max, Up: Function ABI Documentation
8.2.34 `_gfortran_caf_co_min' -- Collective minimum reduction
-------------------------------------------------------------
_Description_:
Calculates for each array element of the variable A the minimum
value for that element in the current team; if RESULT_IMAGE has the
value 0, the result shall be stored on all images, otherwise, only
on the specified image. This function operates on numeric values
and character strings.
_Syntax_:
`void _gfortran_caf_co_min (gfc_descriptor_t *a, int result_image,
int *stat, char *errmsg, int a_len, size_t errmsg_len)'
_Arguments_:
A intent(inout) An array descriptor for the
data to be processed. On the destination
image(s) the result overwrites the old content.
RESULT_IMAGEintent(in) The ID of the image to which the
reduced value should be copied to; if zero, it
has to be copied to all images.
STAT intent(out) Stores the status STAT= and may
be NULL.
ERRMSG intent(out) When an error occurs, this will
be set to an error message; may be NULL.
A_LEN intent(in) the string length of argument A
ERRMSG_LEN intent(in) the buffer size of errmsg
_NOTES_
If RESULT_IMAGE is nonzero, the data in the array descriptor A on
all images except of the specified one become undefined; hence,
the library may make use of this.

File: gfortran.info, Node: _gfortran_caf_co_sum, Next: _gfortran_caf_co_reduce, Prev: _gfortran_caf_co_min, Up: Function ABI Documentation
8.2.35 `_gfortran_caf_co_sum' -- Collective summing reduction
-------------------------------------------------------------
_Description_:
Calculates for each array element of the variable A the sum of all
values for that element in the current team; if RESULT_IMAGE has
the value 0, the result shall be stored on all images, otherwise,
only on the specified image. This function operates on numeric
values only.
_Syntax_:
`void _gfortran_caf_co_sum (gfc_descriptor_t *a, int result_image,
int *stat, char *errmsg, size_t errmsg_len)'
_Arguments_:
A intent(inout) An array descriptor with the
data to be processed. On the destination
image(s) the result overwrites the old content.
RESULT_IMAGEintent(in) The ID of the image to which the
reduced value should be copied to; if zero, it
has to be copied to all images.
STAT intent(out) Stores the status STAT= and may
be NULL.
ERRMSG intent(out) When an error occurs, this will
be set to an error message; may be NULL.
ERRMSG_LEN intent(in) the buffer size of errmsg
_NOTES_
If RESULT_IMAGE is nonzero, the data in the array descriptor A on
all images except of the specified one become undefined; hence,
the library may make use of this.

File: gfortran.info, Node: _gfortran_caf_co_reduce, Prev: _gfortran_caf_co_sum, Up: Function ABI Documentation
8.2.36 `_gfortran_caf_co_reduce' -- Generic collective reduction
----------------------------------------------------------------
_Description_:
Calculates for each array element of the variable A the reduction
value for that element in the current team; if RESULT_IMAGE has the
value 0, the result shall be stored on all images, otherwise, only
on the specified image. The OPR is a pure function doing a
mathematically commutative and associative operation.
The OPR_FLAGS denote the following; the values are bitwise ored.
`GFC_CAF_BYREF' (1) if the result should be returned by reference;
`GFC_CAF_HIDDENLEN' (2) whether the result and argument string
lengths shall be specified as hidden arguments;
`GFC_CAF_ARG_VALUE' (4) whether the arguments shall be passed by
value, `GFC_CAF_ARG_DESC' (8) whether the arguments shall be
passed by descriptor.
_Syntax_:
`void _gfortran_caf_co_reduce (gfc_descriptor_t *a, void * (*opr)
(void *, void *), int opr_flags, int result_image, int *stat, char
*errmsg, int a_len, size_t errmsg_len)'
_Arguments_:
A intent(inout) An array descriptor with the
data to be processed. On the destination
image(s) the result overwrites the old content.
OPR intent(in) Function pointer to the reduction
function
OPR_FLAGS intent(in) Flags regarding the reduction
function
RESULT_IMAGEintent(in) The ID of the image to which the
reduced value should be copied to; if zero, it
has to be copied to all images.
STAT intent(out) Stores the status STAT= and may
be NULL.
ERRMSG intent(out) When an error occurs, this will
be set to an error message; may be NULL.
A_LEN intent(in) the string length of argument A
ERRMSG_LEN intent(in) the buffer size of errmsg
_NOTES_
If RESULT_IMAGE is nonzero, the data in the array descriptor A on
all images except of the specified one become undefined; hence,
the library may make use of this.
For character arguments, the result is passed as first argument,
followed by the result string length, next come the two string
arguments, followed by the two hidden string length arguments.
With C binding, there are no hidden arguments and by-reference
passing and either only a single character is passed or an array
descriptor.

File: gfortran.info, Node: Intrinsic Procedures, Next: Intrinsic Modules, Prev: Coarray Programming, Up: Top
9 Intrinsic Procedures
**********************
* Menu:
* Introduction: Introduction to Intrinsics
* `ABORT': ABORT, Abort the program
* `ABS': ABS, Absolute value
* `ACCESS': ACCESS, Checks file access modes
* `ACHAR': ACHAR, Character in ASCII collating sequence
* `ACOS': ACOS, Arccosine function
* `ACOSD': ACOSD, Arccosine function, degrees
* `ACOSH': ACOSH, Inverse hyperbolic cosine function
* `ADJUSTL': ADJUSTL, Left adjust a string
* `ADJUSTR': ADJUSTR, Right adjust a string
* `AIMAG': AIMAG, Imaginary part of complex number
* `AINT': AINT, Truncate to a whole number
* `ALARM': ALARM, Set an alarm clock
* `ALL': ALL, Determine if all values are true
* `ALLOCATED': ALLOCATED, Status of allocatable entity
* `AND': AND, Bitwise logical AND
* `ANINT': ANINT, Nearest whole number
* `ANY': ANY, Determine if any values are true
* `ASIN': ASIN, Arcsine function
* `ASIND': ASIND, Arcsine function, degrees
* `ASINH': ASINH, Inverse hyperbolic sine function
* `ASSOCIATED': ASSOCIATED, Status of a pointer or pointer/target pair
* `ATAN': ATAN, Arctangent function
* `ATAND': ATAND, Arctangent function, degrees
* `ATAN2': ATAN2, Arctangent function
* `ATAN2D': ATAN2D, Arctangent function, degrees
* `ATANH': ATANH, Inverse hyperbolic tangent function
* `ATOMIC_ADD': ATOMIC_ADD, Atomic ADD operation
* `ATOMIC_AND': ATOMIC_AND, Atomic bitwise AND operation
* `ATOMIC_CAS': ATOMIC_CAS, Atomic compare and swap
* `ATOMIC_DEFINE': ATOMIC_DEFINE, Setting a variable atomically
* `ATOMIC_FETCH_ADD': ATOMIC_FETCH_ADD, Atomic ADD operation with prior fetch
* `ATOMIC_FETCH_AND': ATOMIC_FETCH_AND, Atomic bitwise AND operation with prior fetch
* `ATOMIC_FETCH_OR': ATOMIC_FETCH_OR, Atomic bitwise OR operation with prior fetch
* `ATOMIC_FETCH_XOR': ATOMIC_FETCH_XOR, Atomic bitwise XOR operation with prior fetch
* `ATOMIC_OR': ATOMIC_OR, Atomic bitwise OR operation
* `ATOMIC_REF': ATOMIC_REF, Obtaining the value of a variable atomically
* `ATOMIC_XOR': ATOMIC_XOR, Atomic bitwise OR operation
* `BACKTRACE': BACKTRACE, Show a backtrace
* `BESSEL_J0': BESSEL_J0, Bessel function of the first kind of order 0
* `BESSEL_J1': BESSEL_J1, Bessel function of the first kind of order 1
* `BESSEL_JN': BESSEL_JN, Bessel function of the first kind
* `BESSEL_Y0': BESSEL_Y0, Bessel function of the second kind of order 0
* `BESSEL_Y1': BESSEL_Y1, Bessel function of the second kind of order 1
* `BESSEL_YN': BESSEL_YN, Bessel function of the second kind
* `BGE': BGE, Bitwise greater than or equal to
* `BGT': BGT, Bitwise greater than
* `BIT_SIZE': BIT_SIZE, Bit size inquiry function
* `BLE': BLE, Bitwise less than or equal to
* `BLT': BLT, Bitwise less than
* `BTEST': BTEST, Bit test function
* `C_ASSOCIATED': C_ASSOCIATED, Status of a C pointer
* `C_F_POINTER': C_F_POINTER, Convert C into Fortran pointer
* `C_F_PROCPOINTER': C_F_PROCPOINTER, Convert C into Fortran procedure pointer
* `C_FUNLOC': C_FUNLOC, Obtain the C address of a procedure
* `C_LOC': C_LOC, Obtain the C address of an object
* `C_SIZEOF': C_SIZEOF, Size in bytes of an expression
* `CEILING': CEILING, Integer ceiling function
* `CHAR': CHAR, Integer-to-character conversion function
* `CHDIR': CHDIR, Change working directory
* `CHMOD': CHMOD, Change access permissions of files
* `CMPLX': CMPLX, Complex conversion function
* `CO_BROADCAST': CO_BROADCAST, Copy a value to all images the current set of images
* `CO_MAX': CO_MAX, Maximal value on the current set of images
* `CO_MIN': CO_MIN, Minimal value on the current set of images
* `CO_REDUCE': CO_REDUCE, Reduction of values on the current set of images
* `CO_SUM': CO_SUM, Sum of values on the current set of images
* `COMMAND_ARGUMENT_COUNT': COMMAND_ARGUMENT_COUNT, Get number of command line arguments
* `COMPILER_OPTIONS': COMPILER_OPTIONS, Options passed to the compiler
* `COMPILER_VERSION': COMPILER_VERSION, Compiler version string
* `COMPLEX': COMPLEX, Complex conversion function
* `CONJG': CONJG, Complex conjugate function
* `COS': COS, Cosine function
* `COSD': COSD, Cosine function, degrees
* `COSH': COSH, Hyperbolic cosine function
* `COTAN': COTAN, Cotangent function
* `COTAND': COTAND, Cotangent function, degrees
* `COUNT': COUNT, Count occurrences of TRUE in an array
* `CPU_TIME': CPU_TIME, CPU time subroutine
* `CSHIFT': CSHIFT, Circular shift elements of an array
* `CTIME': CTIME, Subroutine (or function) to convert a time into a string
* `DATE_AND_TIME': DATE_AND_TIME, Date and time subroutine
* `DBLE': DBLE, Double precision conversion function
* `DCMPLX': DCMPLX, Double complex conversion function
* `DIGITS': DIGITS, Significant digits function
* `DIM': DIM, Positive difference
* `DOT_PRODUCT': DOT_PRODUCT, Dot product function
* `DPROD': DPROD, Double product function
* `DREAL': DREAL, Double real part function
* `DSHIFTL': DSHIFTL, Combined left shift
* `DSHIFTR': DSHIFTR, Combined right shift
* `DTIME': DTIME, Execution time subroutine (or function)
* `EOSHIFT': EOSHIFT, End-off shift elements of an array
* `EPSILON': EPSILON, Epsilon function
* `ERF': ERF, Error function
* `ERFC': ERFC, Complementary error function
* `ERFC_SCALED': ERFC_SCALED, Exponentially-scaled complementary error function
* `ETIME': ETIME, Execution time subroutine (or function)
* `EVENT_QUERY': EVENT_QUERY, Query whether a coarray event has occurred
* `EXECUTE_COMMAND_LINE': EXECUTE_COMMAND_LINE, Execute a shell command
* `EXIT': EXIT, Exit the program with status.
* `EXP': EXP, Exponential function
* `EXPONENT': EXPONENT, Exponent function
* `EXTENDS_TYPE_OF': EXTENDS_TYPE_OF, Query dynamic type for extension
* `FDATE': FDATE, Subroutine (or function) to get the current time as a string
* `FGET': FGET, Read a single character in stream mode from stdin
* `FGETC': FGETC, Read a single character in stream mode
* `FINDLOC': FINDLOC, Search an array for a value
* `FLOOR': FLOOR, Integer floor function
* `FLUSH': FLUSH, Flush I/O unit(s)
* `FNUM': FNUM, File number function
* `FPUT': FPUT, Write a single character in stream mode to stdout
* `FPUTC': FPUTC, Write a single character in stream mode
* `FRACTION': FRACTION, Fractional part of the model representation
* `FREE': FREE, Memory de-allocation subroutine
* `FSEEK': FSEEK, Low level file positioning subroutine
* `FSTAT': FSTAT, Get file status
* `FTELL': FTELL, Current stream position
* `GAMMA': GAMMA, Gamma function
* `GERROR': GERROR, Get last system error message
* `GETARG': GETARG, Get command line arguments
* `GET_COMMAND': GET_COMMAND, Get the entire command line
* `GET_COMMAND_ARGUMENT': GET_COMMAND_ARGUMENT, Get command line arguments
* `GETCWD': GETCWD, Get current working directory
* `GETENV': GETENV, Get an environmental variable
* `GET_ENVIRONMENT_VARIABLE': GET_ENVIRONMENT_VARIABLE, Get an environmental variable
* `GETGID': GETGID, Group ID function
* `GETLOG': GETLOG, Get login name
* `GETPID': GETPID, Process ID function
* `GETUID': GETUID, User ID function
* `GMTIME': GMTIME, Convert time to GMT info
* `HOSTNM': HOSTNM, Get system host name
* `HUGE': HUGE, Largest number of a kind
* `HYPOT': HYPOT, Euclidean distance function
* `IACHAR': IACHAR, Code in ASCII collating sequence
* `IALL': IALL, Bitwise AND of array elements
* `IAND': IAND, Bitwise logical and
* `IANY': IANY, Bitwise OR of array elements
* `IARGC': IARGC, Get the number of command line arguments
* `IBCLR': IBCLR, Clear bit
* `IBITS': IBITS, Bit extraction
* `IBSET': IBSET, Set bit
* `ICHAR': ICHAR, Character-to-integer conversion function
* `IDATE': IDATE, Current local time (day/month/year)
* `IEOR': IEOR, Bitwise logical exclusive or
* `IERRNO': IERRNO, Function to get the last system error number
* `IMAGE_INDEX': IMAGE_INDEX, Cosubscript to image index conversion
* `INDEX': INDEX intrinsic, Position of a substring within a string
* `INT': INT, Convert to integer type
* `INT2': INT2, Convert to 16-bit integer type
* `INT8': INT8, Convert to 64-bit integer type
* `IOR': IOR, Bitwise logical or
* `IPARITY': IPARITY, Bitwise XOR of array elements
* `IRAND': IRAND, Integer pseudo-random number
* `IS_CONTIGUOUS': IS_CONTIGUOUS, Test whether an array is contiguous
* `IS_IOSTAT_END': IS_IOSTAT_END, Test for end-of-file value
* `IS_IOSTAT_EOR': IS_IOSTAT_EOR, Test for end-of-record value
* `ISATTY': ISATTY, Whether a unit is a terminal device
* `ISHFT': ISHFT, Shift bits
* `ISHFTC': ISHFTC, Shift bits circularly
* `ISNAN': ISNAN, Tests for a NaN
* `ITIME': ITIME, Current local time (hour/minutes/seconds)
* `KILL': KILL, Send a signal to a process
* `KIND': KIND, Kind of an entity
* `LBOUND': LBOUND, Lower dimension bounds of an array
* `LCOBOUND': LCOBOUND, Lower codimension bounds of an array
* `LEADZ': LEADZ, Number of leading zero bits of an integer
* `LEN': LEN, Length of a character entity
* `LEN_TRIM': LEN_TRIM, Length of a character entity without trailing blank characters
* `LGE': LGE, Lexical greater than or equal
* `LGT': LGT, Lexical greater than
* `LINK': LINK, Create a hard link
* `LLE': LLE, Lexical less than or equal
* `LLT': LLT, Lexical less than
* `LNBLNK': LNBLNK, Index of the last non-blank character in a string
* `LOC': LOC, Returns the address of a variable
* `LOG': LOG, Logarithm function
* `LOG10': LOG10, Base 10 logarithm function
* `LOG_GAMMA': LOG_GAMMA, Logarithm of the Gamma function
* `LOGICAL': LOGICAL, Convert to logical type
* `LONG': LONG, Convert to integer type
* `LSHIFT': LSHIFT, Left shift bits
* `LSTAT': LSTAT, Get file status
* `LTIME': LTIME, Convert time to local time info
* `MALLOC': MALLOC, Dynamic memory allocation function
* `MASKL': MASKL, Left justified mask
* `MASKR': MASKR, Right justified mask
* `MATMUL': MATMUL, matrix multiplication
* `MAX': MAX, Maximum value of an argument list
* `MAXEXPONENT': MAXEXPONENT, Maximum exponent of a real kind
* `MAXLOC': MAXLOC, Location of the maximum value within an array
* `MAXVAL': MAXVAL, Maximum value of an array
* `MCLOCK': MCLOCK, Time function
* `MCLOCK8': MCLOCK8, Time function (64-bit)
* `MERGE': MERGE, Merge arrays
* `MERGE_BITS': MERGE_BITS, Merge of bits under mask
* `MIN': MIN, Minimum value of an argument list
* `MINEXPONENT': MINEXPONENT, Minimum exponent of a real kind
* `MINLOC': MINLOC, Location of the minimum value within an array
* `MINVAL': MINVAL, Minimum value of an array
* `MOD': MOD, Remainder function
* `MODULO': MODULO, Modulo function
* `MOVE_ALLOC': MOVE_ALLOC, Move allocation from one object to another
* `MVBITS': MVBITS, Move bits from one integer to another
* `NEAREST': NEAREST, Nearest representable number
* `NEW_LINE': NEW_LINE, New line character
* `NINT': NINT, Nearest whole number
* `NORM2': NORM2, Euclidean vector norm
* `NOT': NOT, Logical negation
* `NULL': NULL, Function that returns an disassociated pointer
* `NUM_IMAGES': NUM_IMAGES, Number of images
* `OR': OR, Bitwise logical OR
* `PACK': PACK, Pack an array into an array of rank one
* `PARITY': PARITY, Reduction with exclusive OR
* `PERROR': PERROR, Print system error message
* `POPCNT': POPCNT, Number of bits set
* `POPPAR': POPPAR, Parity of the number of bits set
* `PRECISION': PRECISION, Decimal precision of a real kind
* `PRESENT': PRESENT, Determine whether an optional dummy argument is specified
* `PRODUCT': PRODUCT, Product of array elements
* `RADIX': RADIX, Base of a data model
* `RAN': RAN, Real pseudo-random number
* `RAND': RAND, Real pseudo-random number
* `RANDOM_INIT': RANDOM_INIT, Initialize pseudo-random number generator
* `RANDOM_NUMBER': RANDOM_NUMBER, Pseudo-random number
* `RANDOM_SEED': RANDOM_SEED, Initialize a pseudo-random number sequence
* `RANGE': RANGE, Decimal exponent range
* `RANK' : RANK, Rank of a data object
* `REAL': REAL, Convert to real type
* `RENAME': RENAME, Rename a file
* `REPEAT': REPEAT, Repeated string concatenation
* `RESHAPE': RESHAPE, Function to reshape an array
* `RRSPACING': RRSPACING, Reciprocal of the relative spacing
* `RSHIFT': RSHIFT, Right shift bits
* `SAME_TYPE_AS': SAME_TYPE_AS, Query dynamic types for equality
* `SCALE': SCALE, Scale a real value
* `SCAN': SCAN, Scan a string for the presence of a set of characters
* `SECNDS': SECNDS, Time function
* `SECOND': SECOND, CPU time function
* `SELECTED_CHAR_KIND': SELECTED_CHAR_KIND, Choose character kind
* `SELECTED_INT_KIND': SELECTED_INT_KIND, Choose integer kind
* `SELECTED_REAL_KIND': SELECTED_REAL_KIND, Choose real kind
* `SET_EXPONENT': SET_EXPONENT, Set the exponent of the model
* `SHAPE': SHAPE, Determine the shape of an array
* `SHIFTA': SHIFTA, Right shift with fill
* `SHIFTL': SHIFTL, Left shift
* `SHIFTR': SHIFTR, Right shift
* `SIGN': SIGN, Sign copying function
* `SIGNAL': SIGNAL, Signal handling subroutine (or function)
* `SIN': SIN, Sine function
* `SIND': SIND, Sine function, degrees
* `SINH': SINH, Hyperbolic sine function
* `SIZE': SIZE, Function to determine the size of an array
* `SIZEOF': SIZEOF, Determine the size in bytes of an expression
* `SLEEP': SLEEP, Sleep for the specified number of seconds
* `SPACING': SPACING, Smallest distance between two numbers of a given type
* `SPREAD': SPREAD, Add a dimension to an array
* `SQRT': SQRT, Square-root function
* `SRAND': SRAND, Reinitialize the random number generator
* `STAT': STAT, Get file status
* `STORAGE_SIZE': STORAGE_SIZE, Storage size in bits
* `SUM': SUM, Sum of array elements
* `SYMLNK': SYMLNK, Create a symbolic link
* `SYSTEM': SYSTEM, Execute a shell command
* `SYSTEM_CLOCK': SYSTEM_CLOCK, Time function
* `TAN': TAN, Tangent function
* `TAND': TAND, Tangent function, degrees
* `TANH': TANH, Hyperbolic tangent function
* `THIS_IMAGE': THIS_IMAGE, Cosubscript index of this image
* `TIME': TIME, Time function
* `TIME8': TIME8, Time function (64-bit)
* `TINY': TINY, Smallest positive number of a real kind
* `TRAILZ': TRAILZ, Number of trailing zero bits of an integer
* `TRANSFER': TRANSFER, Transfer bit patterns
* `TRANSPOSE': TRANSPOSE, Transpose an array of rank two
* `TRIM': TRIM, Remove trailing blank characters of a string
* `TTYNAM': TTYNAM, Get the name of a terminal device.
* `UBOUND': UBOUND, Upper dimension bounds of an array
* `UCOBOUND': UCOBOUND, Upper codimension bounds of an array
* `UMASK': UMASK, Set the file creation mask
* `UNLINK': UNLINK, Remove a file from the file system
* `UNPACK': UNPACK, Unpack an array of rank one into an array
* `VERIFY': VERIFY, Scan a string for the absence of a set of characters
* `XOR': XOR, Bitwise logical exclusive or

File: gfortran.info, Node: Introduction to Intrinsics, Next: ABORT, Up: Intrinsic Procedures
9.1 Introduction to intrinsic procedures
========================================
The intrinsic procedures provided by GNU Fortran include all of the
intrinsic procedures required by the Fortran 95 standard, a set of
intrinsic procedures for backwards compatibility with G77, and a
selection of intrinsic procedures from the Fortran 2003 and Fortran 2008
standards. Any conflict between a description here and a description in
either the Fortran 95 standard, the Fortran 2003 standard or the Fortran
2008 standard is unintentional, and the standard(s) should be considered
authoritative.
The enumeration of the `KIND' type parameter is processor defined in
the Fortran 95 standard. GNU Fortran defines the default integer type
and default real type by `INTEGER(KIND=4)' and `REAL(KIND=4)',
respectively. The standard mandates that both data types shall have
another kind, which have more precision. On typical target
architectures supported by `gfortran', this kind type parameter is
`KIND=8'. Hence, `REAL(KIND=8)' and `DOUBLE PRECISION' are equivalent.
In the description of generic intrinsic procedures, the kind type
parameter will be specified by `KIND=*', and in the description of
specific names for an intrinsic procedure the kind type parameter will
be explicitly given (e.g., `REAL(KIND=4)' or `REAL(KIND=8)'). Finally,
for brevity the optional `KIND=' syntax will be omitted.
Many of the intrinsic procedures take one or more optional arguments.
This document follows the convention used in the Fortran 95 standard,
and denotes such arguments by square brackets.
GNU Fortran offers the `-std=f95' and `-std=gnu' options, which can
be used to restrict the set of intrinsic procedures to a given
standard. By default, `gfortran' sets the `-std=gnu' option, and so
all intrinsic procedures described here are accepted. There is one
caveat. For a select group of intrinsic procedures, `g77' implemented
both a function and a subroutine. Both classes have been implemented
in `gfortran' for backwards compatibility with `g77'. It is noted here
that these functions and subroutines cannot be intermixed in a given
subprogram. In the descriptions that follow, the applicable standard
for each intrinsic procedure is noted.

File: gfortran.info, Node: ABORT, Next: ABS, Prev: Introduction to Intrinsics, Up: Intrinsic Procedures
9.2 `ABORT' -- Abort the program
================================
_Description_:
`ABORT' causes immediate termination of the program. On operating
systems that support a core dump, `ABORT' will produce a core dump.
It will also print a backtrace, unless `-fno-backtrace' is given.
_Standard_:
GNU extension
_Class_:
Subroutine
_Syntax_:
`CALL ABORT'
_Return value_:
Does not return.
_Example_:
program test_abort
integer :: i = 1, j = 2
if (i /= j) call abort
end program test_abort
_See also_:
*note EXIT::, *note KILL::, *note BACKTRACE::

File: gfortran.info, Node: ABS, Next: ACCESS, Prev: ABORT, Up: Intrinsic Procedures
9.3 `ABS' -- Absolute value
===========================
_Description_:
`ABS(A)' computes the absolute value of `A'.
_Standard_:
Fortran 77 and later, has overloads that are GNU extensions
_Class_:
Elemental function
_Syntax_:
`RESULT = ABS(A)'
_Arguments_:
A The type of the argument shall be an `INTEGER',
`REAL', or `COMPLEX'.
_Return value_:
The return value is of the same type and kind as the argument
except the return value is `REAL' for a `COMPLEX' argument.
_Example_:
program test_abs
integer :: i = -1
real :: x = -1.e0
complex :: z = (-1.e0,0.e0)
i = abs(i)
x = abs(x)
x = abs(z)
end program test_abs
_Specific names_:
Name Argument Return type Standard
`ABS(A)' `REAL(4) A' `REAL(4)' Fortran 77 and
later
`CABS(A)' `COMPLEX(4) `REAL(4)' Fortran 77 and
A' later
`DABS(A)' `REAL(8) A' `REAL(8)' Fortran 77 and
later
`IABS(A)' `INTEGER(4) `INTEGER(4)' Fortran 77 and
A' later
`BABS(A)' `INTEGER(1) `INTEGER(1)' GNU extension
A'
`IIABS(A)' `INTEGER(2) `INTEGER(2)' GNU extension
A'
`JIABS(A)' `INTEGER(4) `INTEGER(4)' GNU extension
A'
`KIABS(A)' `INTEGER(8) `INTEGER(8)' GNU extension
A'
`ZABS(A)' `COMPLEX(8) `COMPLEX(8)' GNU extension
A'
`CDABS(A)' `COMPLEX(8) `COMPLEX(8)' GNU extension
A'

File: gfortran.info, Node: ACCESS, Next: ACHAR, Prev: ABS, Up: Intrinsic Procedures
9.4 `ACCESS' -- Checks file access modes
========================================
_Description_:
`ACCESS(NAME, MODE)' checks whether the file NAME exists, is
readable, writable or executable. Except for the executable check,
`ACCESS' can be replaced by Fortran 95's `INQUIRE'.
_Standard_:
GNU extension
_Class_:
Inquiry function
_Syntax_:
`RESULT = ACCESS(NAME, MODE)'
_Arguments_:
NAME Scalar `CHARACTER' of default kind with the
file name. Tailing blank are ignored unless
the character `achar(0)' is present, then all
characters up to and excluding `achar(0)' are
used as file name.
MODE Scalar `CHARACTER' of default kind with the
file access mode, may be any concatenation of
`"r"' (readable), `"w"' (writable) and `"x"'
(executable), or `" "' to check for existence.
_Return value_:
Returns a scalar `INTEGER', which is `0' if the file is accessible
in the given mode; otherwise or if an invalid argument has been
given for `MODE' the value `1' is returned.
_Example_:
program access_test
implicit none
character(len=*), parameter :: file = 'test.dat'
character(len=*), parameter :: file2 = 'test.dat '//achar(0)
if(access(file,' ') == 0) print *, trim(file),' is exists'
if(access(file,'r') == 0) print *, trim(file),' is readable'
if(access(file,'w') == 0) print *, trim(file),' is writable'
if(access(file,'x') == 0) print *, trim(file),' is executable'
if(access(file2,'rwx') == 0) &
print *, trim(file2),' is readable, writable and executable'
end program access_test
_Specific names_:
_See also_:

File: gfortran.info, Node: ACHAR, Next: ACOS, Prev: ACCESS, Up: Intrinsic Procedures
9.5 `ACHAR' -- Character in ASCII collating sequence
====================================================
_Description_:
`ACHAR(I)' returns the character located at position `I' in the
ASCII collating sequence.
_Standard_:
Fortran 77 and later, with KIND argument Fortran 2003 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = ACHAR(I [, KIND])'
_Arguments_:
I The type shall be `INTEGER'.
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
_Return value_:
The return value is of type `CHARACTER' with a length of one. If
the KIND argument is present, the return value is of the specified
kind and of the default kind otherwise.
_Example_:
program test_achar
character c
c = achar(32)
end program test_achar
_Note_:
See *note ICHAR:: for a discussion of converting between numerical
values and formatted string representations.
_See also_:
*note CHAR::, *note IACHAR::, *note ICHAR::

File: gfortran.info, Node: ACOS, Next: ACOSD, Prev: ACHAR, Up: Intrinsic Procedures
9.6 `ACOS' -- Arccosine function
================================
_Description_:
`ACOS(X)' computes the arccosine of X (inverse of `COS(X)').
_Standard_:
Fortran 77 and later, for a complex argument Fortran 2008 or later
_Class_:
Elemental function
_Syntax_:
`RESULT = ACOS(X)'
_Arguments_:
X The type shall either be `REAL' with a
magnitude that is less than or equal to one -
or the type shall be `COMPLEX'.
_Return value_:
The return value is of the same type and kind as X. The real part
of the result is in radians and lies in the range 0 \leq \Re
\acos(x) \leq \pi.
_Example_:
program test_acos
real(8) :: x = 0.866_8
x = acos(x)
end program test_acos
_Specific names_:
Name Argument Return type Standard
`ACOS(X)' `REAL(4) X' `REAL(4)' Fortran 77 and
later
`DACOS(X)' `REAL(8) X' `REAL(8)' Fortran 77 and
later
_See also_:
Inverse function: *note COS:: Degrees function: *note ACOSD::

File: gfortran.info, Node: ACOSD, Next: ACOSH, Prev: ACOS, Up: Intrinsic Procedures
9.7 `ACOSD' -- Arccosine function, degrees
==========================================
_Description_:
`ACOSD(X)' computes the arccosine of X in degrees (inverse of
`COSD(X)').
This function is for compatibility only and should be avoided in
favor of standard constructs wherever possible.
_Standard_:
GNU Extension, enabled with `-fdec-math'
_Class_:
Elemental function
_Syntax_:
`RESULT = ACOSD(X)'
_Arguments_:
X The type shall either be `REAL' with a
magnitude that is less than or equal to one -
or the type shall be `COMPLEX'.
_Return value_:
The return value is of the same type and kind as X. The real part
of the result is in degrees and lies in the range 0 \leq \Re
\acos(x) \leq 180.
_Example_:
program test_acosd
real(8) :: x = 0.866_8
x = acosd(x)
end program test_acosd
_Specific names_:
Name Argument Return type Standard
`ACOSD(X)' `REAL(4) X' `REAL(4)' GNU Extension
`DACOSD(X)' `REAL(8) X' `REAL(8)' GNU Extension
_See also_:
Inverse function: *note COSD:: Radians function: *note ACOS::

File: gfortran.info, Node: ACOSH, Next: ADJUSTL, Prev: ACOSD, Up: Intrinsic Procedures
9.8 `ACOSH' -- Inverse hyperbolic cosine function
=================================================
_Description_:
`ACOSH(X)' computes the inverse hyperbolic cosine of X.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = ACOSH(X)'
_Arguments_:
X The type shall be `REAL' or `COMPLEX'.
_Return value_:
The return value has the same type and kind as X. If X is complex,
the imaginary part of the result is in radians and lies between 0
\leq \Im \acosh(x) \leq \pi.
_Example_:
PROGRAM test_acosh
REAL(8), DIMENSION(3) :: x = (/ 1.0, 2.0, 3.0 /)
WRITE (*,*) ACOSH(x)
END PROGRAM
_Specific names_:
Name Argument Return type Standard
`DACOSH(X)' `REAL(8) X' `REAL(8)' GNU extension
_See also_:
Inverse function: *note COSH::

File: gfortran.info, Node: ADJUSTL, Next: ADJUSTR, Prev: ACOSH, Up: Intrinsic Procedures
9.9 `ADJUSTL' -- Left adjust a string
=====================================
_Description_:
`ADJUSTL(STRING)' will left adjust a string by removing leading
spaces. Spaces are inserted at the end of the string as needed.
_Standard_:
Fortran 90 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = ADJUSTL(STRING)'
_Arguments_:
STRING The type shall be `CHARACTER'.
_Return value_:
The return value is of type `CHARACTER' and of the same kind as
STRING where leading spaces are removed and the same number of
spaces are inserted on the end of STRING.
_Example_:
program test_adjustl
character(len=20) :: str = ' gfortran'
str = adjustl(str)
print *, str
end program test_adjustl
_See also_:
*note ADJUSTR::, *note TRIM::

File: gfortran.info, Node: ADJUSTR, Next: AIMAG, Prev: ADJUSTL, Up: Intrinsic Procedures
9.10 `ADJUSTR' -- Right adjust a string
=======================================
_Description_:
`ADJUSTR(STRING)' will right adjust a string by removing trailing
spaces. Spaces are inserted at the start of the string as needed.
_Standard_:
Fortran 95 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = ADJUSTR(STRING)'
_Arguments_:
STR The type shall be `CHARACTER'.
_Return value_:
The return value is of type `CHARACTER' and of the same kind as
STRING where trailing spaces are removed and the same number of
spaces are inserted at the start of STRING.
_Example_:
program test_adjustr
character(len=20) :: str = 'gfortran'
str = adjustr(str)
print *, str
end program test_adjustr
_See also_:
*note ADJUSTL::, *note TRIM::

File: gfortran.info, Node: AIMAG, Next: AINT, Prev: ADJUSTR, Up: Intrinsic Procedures
9.11 `AIMAG' -- Imaginary part of complex number
================================================
_Description_:
`AIMAG(Z)' yields the imaginary part of complex argument `Z'. The
`IMAG(Z)' and `IMAGPART(Z)' intrinsic functions are provided for
compatibility with `g77', and their use in new code is strongly
discouraged.
_Standard_:
Fortran 77 and later, has overloads that are GNU extensions
_Class_:
Elemental function
_Syntax_:
`RESULT = AIMAG(Z)'
_Arguments_:
Z The type of the argument shall be `COMPLEX'.
_Return value_:
The return value is of type `REAL' with the kind type parameter of
the argument.
_Example_:
program test_aimag
complex(4) z4
complex(8) z8
z4 = cmplx(1.e0_4, 0.e0_4)
z8 = cmplx(0.e0_8, 1.e0_8)
print *, aimag(z4), dimag(z8)
end program test_aimag
_Specific names_:
Name Argument Return type Standard
`AIMAG(Z)' `COMPLEX Z' `REAL' GNU extension
`DIMAG(Z)' `COMPLEX(8) `REAL(8)' GNU extension
Z'
`IMAG(Z)' `COMPLEX Z' `REAL' GNU extension
`IMAGPART(Z)' `COMPLEX Z' `REAL' GNU extension

File: gfortran.info, Node: AINT, Next: ALARM, Prev: AIMAG, Up: Intrinsic Procedures
9.12 `AINT' -- Truncate to a whole number
=========================================
_Description_:
`AINT(A [, KIND])' truncates its argument to a whole number.
_Standard_:
Fortran 77 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = AINT(A [, KIND])'
_Arguments_:
A The type of the argument shall be `REAL'.
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
_Return value_:
The return value is of type `REAL' with the kind type parameter of
the argument if the optional KIND is absent; otherwise, the kind
type parameter will be given by KIND. If the magnitude of X is
less than one, `AINT(X)' returns zero. If the magnitude is equal
to or greater than one then it returns the largest whole number
that does not exceed its magnitude. The sign is the same as the
sign of X.
_Example_:
program test_aint
real(4) x4
real(8) x8
x4 = 1.234E0_4
x8 = 4.321_8
print *, aint(x4), dint(x8)
x8 = aint(x4,8)
end program test_aint
_Specific names_:
Name Argument Return type Standard
`AINT(A)' `REAL(4) A' `REAL(4)' Fortran 77 and
later
`DINT(A)' `REAL(8) A' `REAL(8)' Fortran 77 and
later

File: gfortran.info, Node: ALARM, Next: ALL, Prev: AINT, Up: Intrinsic Procedures
9.13 `ALARM' -- Execute a routine after a given delay
=====================================================
_Description_:
`ALARM(SECONDS, HANDLER [, STATUS])' causes external subroutine
HANDLER to be executed after a delay of SECONDS by using
`alarm(2)' to set up a signal and `signal(2)' to catch it. If
STATUS is supplied, it will be returned with the number of seconds
remaining until any previously scheduled alarm was due to be
delivered, or zero if there was no previously scheduled alarm.
_Standard_:
GNU extension
_Class_:
Subroutine
_Syntax_:
`CALL ALARM(SECONDS, HANDLER [, STATUS])'
_Arguments_:
SECONDS The type of the argument shall be a scalar
`INTEGER'. It is `INTENT(IN)'.
HANDLER Signal handler (`INTEGER FUNCTION' or
`SUBROUTINE') or dummy/global `INTEGER'
scalar. The scalar values may be either
`SIG_IGN=1' to ignore the alarm generated or
`SIG_DFL=0' to set the default action. It is
`INTENT(IN)'.
STATUS (Optional) STATUS shall be a scalar variable
of the default `INTEGER' kind. It is
`INTENT(OUT)'.
_Example_:
program test_alarm
external handler_print
integer i
call alarm (3, handler_print, i)
print *, i
call sleep(10)
end program test_alarm
This will cause the external routine HANDLER_PRINT to be called
after 3 seconds.

File: gfortran.info, Node: ALL, Next: ALLOCATED, Prev: ALARM, Up: Intrinsic Procedures
9.14 `ALL' -- All values in MASK along DIM are true
===================================================
_Description_:
`ALL(MASK [, DIM])' determines if all the values are true in MASK
in the array along dimension DIM.
_Standard_:
Fortran 95 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = ALL(MASK [, DIM])'
_Arguments_:
MASK The type of the argument shall be `LOGICAL' and
it shall not be scalar.
DIM (Optional) DIM shall be a scalar integer with
a value that lies between one and the rank of
MASK.
_Return value_:
`ALL(MASK)' returns a scalar value of type `LOGICAL' where the
kind type parameter is the same as the kind type parameter of
MASK. If DIM is present, then `ALL(MASK, DIM)' returns an array
with the rank of MASK minus 1. The shape is determined from the
shape of MASK where the DIM dimension is elided.
(A)
`ALL(MASK)' is true if all elements of MASK are true. It
also is true if MASK has zero size; otherwise, it is false.
(B)
If the rank of MASK is one, then `ALL(MASK,DIM)' is equivalent
to `ALL(MASK)'. If the rank is greater than one, then
`ALL(MASK,DIM)' is determined by applying `ALL' to the array
sections.
_Example_:
program test_all
logical l
l = all((/.true., .true., .true./))
print *, l
call section
contains
subroutine section
integer a(2,3), b(2,3)
a = 1
b = 1
b(2,2) = 2
print *, all(a .eq. b, 1)
print *, all(a .eq. b, 2)
end subroutine section
end program test_all

File: gfortran.info, Node: ALLOCATED, Next: AND, Prev: ALL, Up: Intrinsic Procedures
9.15 `ALLOCATED' -- Status of an allocatable entity
===================================================
_Description_:
`ALLOCATED(ARRAY)' and `ALLOCATED(SCALAR)' check the allocation
status of ARRAY and SCALAR, respectively.
_Standard_:
Fortran 95 and later. Note, the `SCALAR=' keyword and allocatable
scalar entities are available in Fortran 2003 and later.
_Class_:
Inquiry function
_Syntax_:
`RESULT = ALLOCATED(ARRAY)'
`RESULT = ALLOCATED(SCALAR)'
_Arguments_:
ARRAY The argument shall be an `ALLOCATABLE' array.
SCALAR The argument shall be an `ALLOCATABLE' scalar.
_Return value_:
The return value is a scalar `LOGICAL' with the default logical
kind type parameter. If the argument is allocated, then the
result is `.TRUE.'; otherwise, it returns `.FALSE.'
_Example_:
program test_allocated
integer :: i = 4
real(4), allocatable :: x(:)
if (.not. allocated(x)) allocate(x(i))
end program test_allocated

File: gfortran.info, Node: AND, Next: ANINT, Prev: ALLOCATED, Up: Intrinsic Procedures
9.16 `AND' -- Bitwise logical AND
=================================
_Description_:
Bitwise logical `AND'.
This intrinsic routine is provided for backwards compatibility with
GNU Fortran 77. For integer arguments, programmers should consider
the use of the *note IAND:: intrinsic defined by the Fortran
standard.
_Standard_:
GNU extension
_Class_:
Function
_Syntax_:
`RESULT = AND(I, J)'
_Arguments_:
I The type shall be either a scalar `INTEGER'
type or a scalar `LOGICAL' type or a
boz-literal-constant.
J The type shall be the same as the type of I or
a boz-literal-constant. I and J shall not both
be boz-literal-constants. If either I or J is
a boz-literal-constant, then the other
argument must be a scalar `INTEGER'.
_Return value_:
The return type is either a scalar `INTEGER' or a scalar
`LOGICAL'. If the kind type parameters differ, then the smaller
kind type is implicitly converted to larger kind, and the return
has the larger kind. A boz-literal-constant is converted to an
`INTEGER' with the kind type parameter of the other argument as-if
a call to *note INT:: occurred.
_Example_:
PROGRAM test_and
LOGICAL :: T = .TRUE., F = .FALSE.
INTEGER :: a, b
DATA a / Z'F' /, b / Z'3' /
WRITE (*,*) AND(T, T), AND(T, F), AND(F, T), AND(F, F)
WRITE (*,*) AND(a, b)
END PROGRAM
_See also_:
Fortran 95 elemental function: *note IAND::

File: gfortran.info, Node: ANINT, Next: ANY, Prev: AND, Up: Intrinsic Procedures
9.17 `ANINT' -- Nearest whole number
====================================
_Description_:
`ANINT(A [, KIND])' rounds its argument to the nearest whole
number.
_Standard_:
Fortran 77 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = ANINT(A [, KIND])'
_Arguments_:
A The type of the argument shall be `REAL'.
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
_Return value_:
The return value is of type real with the kind type parameter of
the argument if the optional KIND is absent; otherwise, the kind
type parameter will be given by KIND. If A is greater than zero,
`ANINT(A)' returns `AINT(X+0.5)'. If A is less than or equal to
zero then it returns `AINT(X-0.5)'.
_Example_:
program test_anint
real(4) x4
real(8) x8
x4 = 1.234E0_4
x8 = 4.321_8
print *, anint(x4), dnint(x8)
x8 = anint(x4,8)
end program test_anint
_Specific names_:
Name Argument Return type Standard
`AINT(A)' `REAL(4) A' `REAL(4)' Fortran 77 and
later
`DNINT(A)' `REAL(8) A' `REAL(8)' Fortran 77 and
later

File: gfortran.info, Node: ANY, Next: ASIN, Prev: ANINT, Up: Intrinsic Procedures
9.18 `ANY' -- Any value in MASK along DIM is true
=================================================
_Description_:
`ANY(MASK [, DIM])' determines if any of the values in the logical
array MASK along dimension DIM are `.TRUE.'.
_Standard_:
Fortran 95 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = ANY(MASK [, DIM])'
_Arguments_:
MASK The type of the argument shall be `LOGICAL' and
it shall not be scalar.
DIM (Optional) DIM shall be a scalar integer with
a value that lies between one and the rank of
MASK.
_Return value_:
`ANY(MASK)' returns a scalar value of type `LOGICAL' where the
kind type parameter is the same as the kind type parameter of
MASK. If DIM is present, then `ANY(MASK, DIM)' returns an array
with the rank of MASK minus 1. The shape is determined from the
shape of MASK where the DIM dimension is elided.
(A)
`ANY(MASK)' is true if any element of MASK is true;
otherwise, it is false. It also is false if MASK has zero
size.
(B)
If the rank of MASK is one, then `ANY(MASK,DIM)' is equivalent
to `ANY(MASK)'. If the rank is greater than one, then
`ANY(MASK,DIM)' is determined by applying `ANY' to the array
sections.
_Example_:
program test_any
logical l
l = any((/.true., .true., .true./))
print *, l
call section
contains
subroutine section
integer a(2,3), b(2,3)
a = 1
b = 1
b(2,2) = 2
print *, any(a .eq. b, 1)
print *, any(a .eq. b, 2)
end subroutine section
end program test_any

File: gfortran.info, Node: ASIN, Next: ASIND, Prev: ANY, Up: Intrinsic Procedures
9.19 `ASIN' -- Arcsine function
===============================
_Description_:
`ASIN(X)' computes the arcsine of its X (inverse of `SIN(X)').
_Standard_:
Fortran 77 and later, for a complex argument Fortran 2008 or later
_Class_:
Elemental function
_Syntax_:
`RESULT = ASIN(X)'
_Arguments_:
X The type shall be either `REAL' and a
magnitude that is less than or equal to one -
or be `COMPLEX'.
_Return value_:
The return value is of the same type and kind as X. The real part
of the result is in radians and lies in the range -\pi/2 \leq \Re
\asin(x) \leq \pi/2.
_Example_:
program test_asin
real(8) :: x = 0.866_8
x = asin(x)
end program test_asin
_Specific names_:
Name Argument Return type Standard
`ASIN(X)' `REAL(4) X' `REAL(4)' Fortran 77 and
later
`DASIN(X)' `REAL(8) X' `REAL(8)' Fortran 77 and
later
_See also_:
Inverse function: *note SIN:: Degrees function: *note ASIND::

File: gfortran.info, Node: ASIND, Next: ASINH, Prev: ASIN, Up: Intrinsic Procedures
9.20 `ASIND' -- Arcsine function, degrees
=========================================
_Description_:
`ASIND(X)' computes the arcsine of its X in degrees (inverse of
`SIND(X)').
This function is for compatibility only and should be avoided in
favor of standard constructs wherever possible.
_Standard_:
GNU Extension, enabled with `-fdec-math'.
_Class_:
Elemental function
_Syntax_:
`RESULT = ASIND(X)'
_Arguments_:
X The type shall be either `REAL' and a
magnitude that is less than or equal to one -
or be `COMPLEX'.
_Return value_:
The return value is of the same type and kind as X. The real part
of the result is in degrees and lies in the range -90 \leq \Re
\asin(x) \leq 90.
_Example_:
program test_asind
real(8) :: x = 0.866_8
x = asind(x)
end program test_asind
_Specific names_:
Name Argument Return type Standard
`ASIND(X)' `REAL(4) X' `REAL(4)' GNU Extension
`DASIND(X)' `REAL(8) X' `REAL(8)' GNU Extension
_See also_:
Inverse function: *note SIND:: Radians function: *note ASIN::

File: gfortran.info, Node: ASINH, Next: ASSOCIATED, Prev: ASIND, Up: Intrinsic Procedures
9.21 `ASINH' -- Inverse hyperbolic sine function
================================================
_Description_:
`ASINH(X)' computes the inverse hyperbolic sine of X.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = ASINH(X)'
_Arguments_:
X The type shall be `REAL' or `COMPLEX'.
_Return value_:
The return value is of the same type and kind as X. If X is
complex, the imaginary part of the result is in radians and lies
between -\pi/2 \leq \Im \asinh(x) \leq \pi/2.
_Example_:
PROGRAM test_asinh
REAL(8), DIMENSION(3) :: x = (/ -1.0, 0.0, 1.0 /)
WRITE (*,*) ASINH(x)
END PROGRAM
_Specific names_:
Name Argument Return type Standard
`DASINH(X)' `REAL(8) X' `REAL(8)' GNU extension.
_See also_:
Inverse function: *note SINH::

File: gfortran.info, Node: ASSOCIATED, Next: ATAN, Prev: ASINH, Up: Intrinsic Procedures
9.22 `ASSOCIATED' -- Status of a pointer or pointer/target pair
===============================================================
_Description_:
`ASSOCIATED(POINTER [, TARGET])' determines the status of the
pointer POINTER or if POINTER is associated with the target TARGET.
_Standard_:
Fortran 95 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = ASSOCIATED(POINTER [, TARGET])'
_Arguments_:
POINTER POINTER shall have the `POINTER' attribute and
it can be of any type.
TARGET (Optional) TARGET shall be a pointer or a
target. It must have the same type, kind type
parameter, and array rank as POINTER.
The association status of neither POINTER nor TARGET shall be
undefined.
_Return value_:
`ASSOCIATED(POINTER)' returns a scalar value of type `LOGICAL(4)'.
There are several cases:
(A) When the optional TARGET is not present then
`ASSOCIATED(POINTER)' is true if POINTER is associated with a
target; otherwise, it returns false.
(B) If TARGET is present and a scalar target, the result is true if
TARGET is not a zero-sized storage sequence and the target
associated with POINTER occupies the same storage units. If
POINTER is disassociated, the result is false.
(C) If TARGET is present and an array target, the result is true if
TARGET and POINTER have the same shape, are not zero-sized
arrays, are arrays whose elements are not zero-sized storage
sequences, and TARGET and POINTER occupy the same storage
units in array element order. As in case(B), the result is
false, if POINTER is disassociated.
(D) If TARGET is present and an scalar pointer, the result is true
if TARGET is associated with POINTER, the target associated
with TARGET are not zero-sized storage sequences and occupy
the same storage units. The result is false, if either
TARGET or POINTER is disassociated.
(E) If TARGET is present and an array pointer, the result is true if
target associated with POINTER and the target associated with
TARGET have the same shape, are not zero-sized arrays, are
arrays whose elements are not zero-sized storage sequences,
and TARGET and POINTER occupy the same storage units in array
element order. The result is false, if either TARGET or
POINTER is disassociated.
_Example_:
program test_associated
implicit none
real, target :: tgt(2) = (/1., 2./)
real, pointer :: ptr(:)
ptr => tgt
if (associated(ptr) .eqv. .false.) call abort
if (associated(ptr,tgt) .eqv. .false.) call abort
end program test_associated
_See also_:
*note NULL::

File: gfortran.info, Node: ATAN, Next: ATAND, Prev: ASSOCIATED, Up: Intrinsic Procedures
9.23 `ATAN' -- Arctangent function
==================================
_Description_:
`ATAN(X)' computes the arctangent of X.
_Standard_:
Fortran 77 and later, for a complex argument and for two arguments
Fortran 2008 or later
_Class_:
Elemental function
_Syntax_:
`RESULT = ATAN(X)'
`RESULT = ATAN(Y, X)'
_Arguments_:
X The type shall be `REAL' or `COMPLEX'; if Y is
present, X shall be REAL.
Y shall
be of the
same type
and kind
as X.
_Return value_:
The return value is of the same type and kind as X. If Y is
present, the result is identical to `ATAN2(Y,X)'. Otherwise, it
the arcus tangent of X, where the real part of the result is in
radians and lies in the range -\pi/2 \leq \Re \atan(x) \leq \pi/2.
_Example_:
program test_atan
real(8) :: x = 2.866_8
x = atan(x)
end program test_atan
_Specific names_:
Name Argument Return type Standard
`ATAN(X)' `REAL(4) X' `REAL(4)' Fortran 77 and
later
`DATAN(X)' `REAL(8) X' `REAL(8)' Fortran 77 and
later
_See also_:
Inverse function: *note TAN:: Degrees function: *note ATAND::

File: gfortran.info, Node: ATAND, Next: ATAN2, Prev: ATAN, Up: Intrinsic Procedures
9.24 `ATAND' -- Arctangent function, degrees
============================================
_Description_:
`ATAND(X)' computes the arctangent of X in degrees (inverse of
*note TAND::).
This function is for compatibility only and should be avoided in
favor of standard constructs wherever possible.
_Standard_:
GNU Extension, enabled with `-fdec-math'.
_Class_:
Elemental function
_Syntax_:
`RESULT = ATAND(X)'
`RESULT = ATAND(Y, X)'
_Arguments_:
X The type shall be `REAL' or `COMPLEX'; if Y is
present, X shall be REAL.
Y shall
be of the
same type
and kind
as X.
_Return value_:
The return value is of the same type and kind as X. If Y is
present, the result is identical to `ATAND2(Y,X)'. Otherwise, it
is the arcus tangent of X, where the real part of the result is in
degrees and lies in the range -90 \leq \Re \atand(x) \leq 90.
_Example_:
program test_atand
real(8) :: x = 2.866_8
x = atand(x)
end program test_atand
_Specific names_:
Name Argument Return type Standard
`ATAND(X)' `REAL(4) X' `REAL(4)' GNU Extension
`DATAND(X)' `REAL(8) X' `REAL(8)' GNU Extension
_See also_:
Inverse function: *note TAND:: Radians function: *note ATAN::

File: gfortran.info, Node: ATAN2, Next: ATAN2D, Prev: ATAND, Up: Intrinsic Procedures
9.25 `ATAN2' -- Arctangent function
===================================
_Description_:
`ATAN2(Y, X)' computes the principal value of the argument
function of the complex number X + i Y. This function can be used
to transform from Cartesian into polar coordinates and allows to
determine the angle in the correct quadrant.
_Standard_:
Fortran 77 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = ATAN2(Y, X)'
_Arguments_:
Y The type shall be `REAL'.
X The type and kind type parameter shall be the
same as Y. If Y is zero, then X must be
nonzero.
_Return value_:
The return value has the same type and kind type parameter as Y. It
is the principal value of the complex number X + i Y. If X is
nonzero, then it lies in the range -\pi \le \atan (x) \leq \pi.
The sign is positive if Y is positive. If Y is zero, then the
return value is zero if X is strictly positive, \pi if X is
negative and Y is positive zero (or the processor does not handle
signed zeros), and -\pi if X is negative and Y is negative zero.
Finally, if X is zero, then the magnitude of the result is \pi/2.
_Example_:
program test_atan2
real(4) :: x = 1.e0_4, y = 0.5e0_4
x = atan2(y,x)
end program test_atan2
_Specific names_:
Name Argument Return type Standard
`ATAN2(X, `REAL(4) X, `REAL(4)' Fortran 77 and
Y)' Y' later
`DATAN2(X, `REAL(8) X, `REAL(8)' Fortran 77 and
Y)' Y' later
_See also_:
Alias: *note ATAN:: Degrees function: *note ATAN2D::

File: gfortran.info, Node: ATAN2D, Next: ATANH, Prev: ATAN2, Up: Intrinsic Procedures
9.26 `ATAN2D' -- Arctangent function, degrees
=============================================
_Description_:
`ATAN2D(Y, X)' computes the principal value of the argument
function of the complex number X + i Y in degrees. This function
can be used to transform from Cartesian into polar coordinates and
allows to determine the angle in the correct quadrant.
This function is for compatibility only and should be avoided in
favor of standard constructs wherever possible.
_Standard_:
GNU Extension, enabled with `-fdec-math'.
_Class_:
Elemental function
_Syntax_:
`RESULT = ATAN2D(Y, X)'
_Arguments_:
Y The type shall be `REAL'.
X The type and kind type parameter shall be the
same as Y. If Y is zero, then X must be
nonzero.
_Return value_:
The return value has the same type and kind type parameter as Y. It
is the principal value of the complex number X + i Y. If X is
nonzero, then it lies in the range -180 \le \atan (x) \leq 180.
The sign is positive if Y is positive. If Y is zero, then the
return value is zero if X is strictly positive, 180 if X is
negative and Y is positive zero (or the processor does not handle
signed zeros), and -180 if X is negative and Y is negative zero.
Finally, if X is zero, then the magnitude of the result is 90.
_Example_:
program test_atan2d
real(4) :: x = 1.e0_4, y = 0.5e0_4
x = atan2d(y,x)
end program test_atan2d
_Specific names_:
Name Argument Return type Standard
`ATAN2D(X, `REAL(4) X, `REAL(4)' GNU Extension
Y)' Y'
`DATAN2D(X, `REAL(8) X, `REAL(8)' GNU Extension
Y)' Y'
_See also_:
Alias: *note ATAND:: Radians function: *note ATAN2::

File: gfortran.info, Node: ATANH, Next: ATOMIC_ADD, Prev: ATAN2D, Up: Intrinsic Procedures
9.27 `ATANH' -- Inverse hyperbolic tangent function
===================================================
_Description_:
`ATANH(X)' computes the inverse hyperbolic tangent of X.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = ATANH(X)'
_Arguments_:
X The type shall be `REAL' or `COMPLEX'.
_Return value_:
The return value has same type and kind as X. If X is complex, the
imaginary part of the result is in radians and lies between -\pi/2
\leq \Im \atanh(x) \leq \pi/2.
_Example_:
PROGRAM test_atanh
REAL, DIMENSION(3) :: x = (/ -1.0, 0.0, 1.0 /)
WRITE (*,*) ATANH(x)
END PROGRAM
_Specific names_:
Name Argument Return type Standard
`DATANH(X)' `REAL(8) X' `REAL(8)' GNU extension
_See also_:
Inverse function: *note TANH::

File: gfortran.info, Node: ATOMIC_ADD, Next: ATOMIC_AND, Prev: ATANH, Up: Intrinsic Procedures
9.28 `ATOMIC_ADD' -- Atomic ADD operation
=========================================
_Description_:
`ATOMIC_ADD(ATOM, VALUE)' atomically adds the value of VAR to the
variable ATOM. When STAT is present and the invocation was
successful, it is assigned the value 0. If it is present and the
invocation has failed, it is assigned a positive value; in
particular, for a coindexed ATOM, if the remote image has stopped,
it is assigned the value of `ISO_FORTRAN_ENV''s
`STAT_STOPPED_IMAGE' and if the remote image has failed, the value
`STAT_FAILED_IMAGE'.
_Standard_:
TS 18508 or later
_Class_:
Atomic subroutine
_Syntax_:
`CALL ATOMIC_ADD (ATOM, VALUE [, STAT])'
_Arguments_:
ATOM Scalar coarray or coindexed variable of integer
type with `ATOMIC_INT_KIND' kind.
VALUE Scalar of the same type as ATOM. If the kind
is different, the value is converted to the
kind of ATOM.
STAT (optional) Scalar default-kind integer
variable.
_Example_:
program atomic
use iso_fortran_env
integer(atomic_int_kind) :: atom[*]
call atomic_add (atom[1], this_image())
end program atomic
_See also_:
*note ATOMIC_DEFINE::, *note ATOMIC_FETCH_ADD::, *note
ISO_FORTRAN_ENV::, *note ATOMIC_AND::, *note ATOMIC_OR::, *note
ATOMIC_XOR::

File: gfortran.info, Node: ATOMIC_AND, Next: ATOMIC_CAS, Prev: ATOMIC_ADD, Up: Intrinsic Procedures
9.29 `ATOMIC_AND' -- Atomic bitwise AND operation
=================================================
_Description_:
`ATOMIC_AND(ATOM, VALUE)' atomically defines ATOM with the bitwise
AND between the values of ATOM and VALUE. When STAT is present and
the invocation was successful, it is assigned the value 0. If it
is present and the invocation has failed, it is assigned a
positive value; in particular, for a coindexed ATOM, if the remote
image has stopped, it is assigned the value of `ISO_FORTRAN_ENV''s
`STAT_STOPPED_IMAGE' and if the remote image has failed, the value
`STAT_FAILED_IMAGE'.
_Standard_:
TS 18508 or later
_Class_:
Atomic subroutine
_Syntax_:
`CALL ATOMIC_AND (ATOM, VALUE [, STAT])'
_Arguments_:
ATOM Scalar coarray or coindexed variable of integer
type with `ATOMIC_INT_KIND' kind.
VALUE Scalar of the same type as ATOM. If the kind
is different, the value is converted to the
kind of ATOM.
STAT (optional) Scalar default-kind integer
variable.
_Example_:
program atomic
use iso_fortran_env
integer(atomic_int_kind) :: atom[*]
call atomic_and (atom[1], int(b'10100011101'))
end program atomic
_See also_:
*note ATOMIC_DEFINE::, *note ATOMIC_FETCH_AND::, *note
ISO_FORTRAN_ENV::, *note ATOMIC_ADD::, *note ATOMIC_OR::, *note
ATOMIC_XOR::

File: gfortran.info, Node: ATOMIC_CAS, Next: ATOMIC_DEFINE, Prev: ATOMIC_AND, Up: Intrinsic Procedures
9.30 `ATOMIC_CAS' -- Atomic compare and swap
============================================
_Description_:
`ATOMIC_CAS' compares the variable ATOM with the value of COMPARE;
if the value is the same, ATOM is set to the value of NEW.
Additionally, OLD is set to the value of ATOM that was used for
the comparison. When STAT is present and the invocation was
successful, it is assigned the value 0. If it is present and the
invocation has failed, it is assigned a positive value; in
particular, for a coindexed ATOM, if the remote image has stopped,
it is assigned the value of `ISO_FORTRAN_ENV''s
`STAT_STOPPED_IMAGE' and if the remote image has failed, the value
`STAT_FAILED_IMAGE'.
_Standard_:
TS 18508 or later
_Class_:
Atomic subroutine
_Syntax_:
`CALL ATOMIC_CAS (ATOM, OLD, COMPARE, NEW [, STAT])'
_Arguments_:
ATOM Scalar coarray or coindexed variable of either
integer type with `ATOMIC_INT_KIND' kind or
logical type with `ATOMIC_LOGICAL_KIND' kind.
OLD Scalar of the same type and kind as ATOM.
COMPARE Scalar variable of the same type and kind as
ATOM.
NEW Scalar variable of the same type as ATOM. If
kind is different, the value is converted to
the kind of ATOM.
STAT (optional) Scalar default-kind integer
variable.
_Example_:
program atomic
use iso_fortran_env
logical(atomic_logical_kind) :: atom[*], prev
call atomic_cas (atom[1], prev, .false., .true.))
end program atomic
_See also_:
*note ATOMIC_DEFINE::, *note ATOMIC_REF::, *note ISO_FORTRAN_ENV::

File: gfortran.info, Node: ATOMIC_DEFINE, Next: ATOMIC_FETCH_ADD, Prev: ATOMIC_CAS, Up: Intrinsic Procedures
9.31 `ATOMIC_DEFINE' -- Setting a variable atomically
=====================================================
_Description_:
`ATOMIC_DEFINE(ATOM, VALUE)' defines the variable ATOM with the
value VALUE atomically. When STAT is present and the invocation was
successful, it is assigned the value 0. If it is present and the
invocation has failed, it is assigned a positive value; in
particular, for a coindexed ATOM, if the remote image has stopped,
it is assigned the value of `ISO_FORTRAN_ENV''s
`STAT_STOPPED_IMAGE' and if the remote image has failed, the value
`STAT_FAILED_IMAGE'.
_Standard_:
Fortran 2008 and later; with STAT, TS 18508 or later
_Class_:
Atomic subroutine
_Syntax_:
`CALL ATOMIC_DEFINE (ATOM, VALUE [, STAT])'
_Arguments_:
ATOM Scalar coarray or coindexed variable of either
integer type with `ATOMIC_INT_KIND' kind or
logical type with `ATOMIC_LOGICAL_KIND' kind.
VALUE Scalar of the same type as ATOM. If the kind
is different, the value is converted to the
kind of ATOM.
STAT (optional) Scalar default-kind integer
variable.
_Example_:
program atomic
use iso_fortran_env
integer(atomic_int_kind) :: atom[*]
call atomic_define (atom[1], this_image())
end program atomic
_See also_:
*note ATOMIC_REF::, *note ATOMIC_CAS::, *note ISO_FORTRAN_ENV::,
*note ATOMIC_ADD::, *note ATOMIC_AND::, *note ATOMIC_OR::, *note
ATOMIC_XOR::

File: gfortran.info, Node: ATOMIC_FETCH_ADD, Next: ATOMIC_FETCH_AND, Prev: ATOMIC_DEFINE, Up: Intrinsic Procedures
9.32 `ATOMIC_FETCH_ADD' -- Atomic ADD operation with prior fetch
================================================================
_Description_:
`ATOMIC_FETCH_ADD(ATOM, VALUE, OLD)' atomically stores the value of
ATOM in OLD and adds the value of VAR to the variable ATOM. When
STAT is present and the invocation was successful, it is assigned
the value 0. If it is present and the invocation has failed, it is
assigned a positive value; in particular, for a coindexed ATOM, if
the remote image has stopped, it is assigned the value of
`ISO_FORTRAN_ENV''s `STAT_STOPPED_IMAGE' and if the remote image
has failed, the value `STAT_FAILED_IMAGE'.
_Standard_:
TS 18508 or later
_Class_:
Atomic subroutine
_Syntax_:
`CALL ATOMIC_FETCH_ADD (ATOM, VALUE, old [, STAT])'
_Arguments_:
ATOM Scalar coarray or coindexed variable of integer
type with `ATOMIC_INT_KIND' kind.
`ATOMIC_LOGICAL_KIND' kind.
VALUE Scalar of the same type as ATOM. If the kind
is different, the value is converted to the
kind of ATOM.
OLD Scalar of the same type and kind as ATOM.
STAT (optional) Scalar default-kind integer
variable.
_Example_:
program atomic
use iso_fortran_env
integer(atomic_int_kind) :: atom[*], old
call atomic_add (atom[1], this_image(), old)
end program atomic
_See also_:
*note ATOMIC_DEFINE::, *note ATOMIC_ADD::, *note ISO_FORTRAN_ENV::,
*note ATOMIC_FETCH_AND::, *note ATOMIC_FETCH_OR::, *note
ATOMIC_FETCH_XOR::

File: gfortran.info, Node: ATOMIC_FETCH_AND, Next: ATOMIC_FETCH_OR, Prev: ATOMIC_FETCH_ADD, Up: Intrinsic Procedures
9.33 `ATOMIC_FETCH_AND' -- Atomic bitwise AND operation with prior fetch
========================================================================
_Description_:
`ATOMIC_AND(ATOM, VALUE)' atomically stores the value of ATOM in
OLD and defines ATOM with the bitwise AND between the values of
ATOM and VALUE. When STAT is present and the invocation was
successful, it is assigned the value 0. If it is present and the
invocation has failed, it is assigned a positive value; in
particular, for a coindexed ATOM, if the remote image has stopped,
it is assigned the value of `ISO_FORTRAN_ENV''s
`STAT_STOPPED_IMAGE' and if the remote image has failed, the value
`STAT_FAILED_IMAGE'.
_Standard_:
TS 18508 or later
_Class_:
Atomic subroutine
_Syntax_:
`CALL ATOMIC_FETCH_AND (ATOM, VALUE, OLD [, STAT])'
_Arguments_:
ATOM Scalar coarray or coindexed variable of integer
type with `ATOMIC_INT_KIND' kind.
VALUE Scalar of the same type as ATOM. If the kind
is different, the value is converted to the
kind of ATOM.
OLD Scalar of the same type and kind as ATOM.
STAT (optional) Scalar default-kind integer
variable.
_Example_:
program atomic
use iso_fortran_env
integer(atomic_int_kind) :: atom[*], old
call atomic_fetch_and (atom[1], int(b'10100011101'), old)
end program atomic
_See also_:
*note ATOMIC_DEFINE::, *note ATOMIC_AND::, *note ISO_FORTRAN_ENV::,
*note ATOMIC_FETCH_ADD::, *note ATOMIC_FETCH_OR::, *note
ATOMIC_FETCH_XOR::

File: gfortran.info, Node: ATOMIC_FETCH_OR, Next: ATOMIC_FETCH_XOR, Prev: ATOMIC_FETCH_AND, Up: Intrinsic Procedures
9.34 `ATOMIC_FETCH_OR' -- Atomic bitwise OR operation with prior fetch
======================================================================
_Description_:
`ATOMIC_OR(ATOM, VALUE)' atomically stores the value of ATOM in
OLD and defines ATOM with the bitwise OR between the values of
ATOM and VALUE. When STAT is present and the invocation was
successful, it is assigned the value 0. If it is present and the
invocation has failed, it is assigned a positive value; in
particular, for a coindexed ATOM, if the remote image has stopped,
it is assigned the value of `ISO_FORTRAN_ENV''s
`STAT_STOPPED_IMAGE' and if the remote image has failed, the value
`STAT_FAILED_IMAGE'.
_Standard_:
TS 18508 or later
_Class_:
Atomic subroutine
_Syntax_:
`CALL ATOMIC_FETCH_OR (ATOM, VALUE, OLD [, STAT])'
_Arguments_:
ATOM Scalar coarray or coindexed variable of integer
type with `ATOMIC_INT_KIND' kind.
VALUE Scalar of the same type as ATOM. If the kind
is different, the value is converted to the
kind of ATOM.
OLD Scalar of the same type and kind as ATOM.
STAT (optional) Scalar default-kind integer
variable.
_Example_:
program atomic
use iso_fortran_env
integer(atomic_int_kind) :: atom[*], old
call atomic_fetch_or (atom[1], int(b'10100011101'), old)
end program atomic
_See also_:
*note ATOMIC_DEFINE::, *note ATOMIC_OR::, *note ISO_FORTRAN_ENV::,
*note ATOMIC_FETCH_ADD::, *note ATOMIC_FETCH_AND::, *note
ATOMIC_FETCH_XOR::

File: gfortran.info, Node: ATOMIC_FETCH_XOR, Next: ATOMIC_OR, Prev: ATOMIC_FETCH_OR, Up: Intrinsic Procedures
9.35 `ATOMIC_FETCH_XOR' -- Atomic bitwise XOR operation with prior fetch
========================================================================
_Description_:
`ATOMIC_XOR(ATOM, VALUE)' atomically stores the value of ATOM in
OLD and defines ATOM with the bitwise XOR between the values of
ATOM and VALUE. When STAT is present and the invocation was
successful, it is assigned the value 0. If it is present and the
invocation has failed, it is assigned a positive value; in
particular, for a coindexed ATOM, if the remote image has stopped,
it is assigned the value of `ISO_FORTRAN_ENV''s
`STAT_STOPPED_IMAGE' and if the remote image has failed, the value
`STAT_FAILED_IMAGE'.
_Standard_:
TS 18508 or later
_Class_:
Atomic subroutine
_Syntax_:
`CALL ATOMIC_FETCH_XOR (ATOM, VALUE, OLD [, STAT])'
_Arguments_:
ATOM Scalar coarray or coindexed variable of integer
type with `ATOMIC_INT_KIND' kind.
VALUE Scalar of the same type as ATOM. If the kind
is different, the value is converted to the
kind of ATOM.
OLD Scalar of the same type and kind as ATOM.
STAT (optional) Scalar default-kind integer
variable.
_Example_:
program atomic
use iso_fortran_env
integer(atomic_int_kind) :: atom[*], old
call atomic_fetch_xor (atom[1], int(b'10100011101'), old)
end program atomic
_See also_:
*note ATOMIC_DEFINE::, *note ATOMIC_XOR::, *note ISO_FORTRAN_ENV::,
*note ATOMIC_FETCH_ADD::, *note ATOMIC_FETCH_AND::, *note
ATOMIC_FETCH_OR::

File: gfortran.info, Node: ATOMIC_OR, Next: ATOMIC_REF, Prev: ATOMIC_FETCH_XOR, Up: Intrinsic Procedures
9.36 `ATOMIC_OR' -- Atomic bitwise OR operation
===============================================
_Description_:
`ATOMIC_OR(ATOM, VALUE)' atomically defines ATOM with the bitwise
AND between the values of ATOM and VALUE. When STAT is present and
the invocation was successful, it is assigned the value 0. If it
is present and the invocation has failed, it is assigned a
positive value; in particular, for a coindexed ATOM, if the remote
image has stopped, it is assigned the value of `ISO_FORTRAN_ENV''s
`STAT_STOPPED_IMAGE' and if the remote image has failed, the value
`STAT_FAILED_IMAGE'.
_Standard_:
TS 18508 or later
_Class_:
Atomic subroutine
_Syntax_:
`CALL ATOMIC_OR (ATOM, VALUE [, STAT])'
_Arguments_:
ATOM Scalar coarray or coindexed variable of integer
type with `ATOMIC_INT_KIND' kind.
VALUE Scalar of the same type as ATOM. If the kind
is different, the value is converted to the
kind of ATOM.
STAT (optional) Scalar default-kind integer
variable.
_Example_:
program atomic
use iso_fortran_env
integer(atomic_int_kind) :: atom[*]
call atomic_or (atom[1], int(b'10100011101'))
end program atomic
_See also_:
*note ATOMIC_DEFINE::, *note ATOMIC_FETCH_OR::, *note
ISO_FORTRAN_ENV::, *note ATOMIC_ADD::, *note ATOMIC_OR::, *note
ATOMIC_XOR::

File: gfortran.info, Node: ATOMIC_REF, Next: ATOMIC_XOR, Prev: ATOMIC_OR, Up: Intrinsic Procedures
9.37 `ATOMIC_REF' -- Obtaining the value of a variable atomically
=================================================================
_Description_:
`ATOMIC_DEFINE(ATOM, VALUE)' atomically assigns the value of the
variable ATOM to VALUE. When STAT is present and the invocation
was successful, it is assigned the value 0. If it is present and
the invocation has failed, it is assigned a positive value; in
particular, for a coindexed ATOM, if the remote image has stopped,
it is assigned the value of `ISO_FORTRAN_ENV''s
`STAT_STOPPED_IMAGE' and if the remote image has failed, the value
`STAT_FAILED_IMAGE'.
_Standard_:
Fortran 2008 and later; with STAT, TS 18508 or later
_Class_:
Atomic subroutine
_Syntax_:
`CALL ATOMIC_REF(VALUE, ATOM [, STAT])'
_Arguments_:
VALUE Scalar of the same type as ATOM. If the kind
is different, the value is converted to the
kind of ATOM.
ATOM Scalar coarray or coindexed variable of either
integer type with `ATOMIC_INT_KIND' kind or
logical type with `ATOMIC_LOGICAL_KIND' kind.
STAT (optional) Scalar default-kind integer
variable.
_Example_:
program atomic
use iso_fortran_env
logical(atomic_logical_kind) :: atom[*]
logical :: val
call atomic_ref (atom, .false.)
! ...
call atomic_ref (atom, val)
if (val) then
print *, "Obtained"
end if
end program atomic
_See also_:
*note ATOMIC_DEFINE::, *note ATOMIC_CAS::, *note ISO_FORTRAN_ENV::,
*note ATOMIC_FETCH_ADD::, *note ATOMIC_FETCH_AND::, *note
ATOMIC_FETCH_OR::, *note ATOMIC_FETCH_XOR::

File: gfortran.info, Node: ATOMIC_XOR, Next: BACKTRACE, Prev: ATOMIC_REF, Up: Intrinsic Procedures
9.38 `ATOMIC_XOR' -- Atomic bitwise OR operation
================================================
_Description_:
`ATOMIC_AND(ATOM, VALUE)' atomically defines ATOM with the bitwise
XOR between the values of ATOM and VALUE. When STAT is present and
the invocation was successful, it is assigned the value 0. If it
is present and the invocation has failed, it is assigned a
positive value; in particular, for a coindexed ATOM, if the remote
image has stopped, it is assigned the value of `ISO_FORTRAN_ENV''s
`STAT_STOPPED_IMAGE' and if the remote image has failed, the value
`STAT_FAILED_IMAGE'.
_Standard_:
TS 18508 or later
_Class_:
Atomic subroutine
_Syntax_:
`CALL ATOMIC_XOR (ATOM, VALUE [, STAT])'
_Arguments_:
ATOM Scalar coarray or coindexed variable of integer
type with `ATOMIC_INT_KIND' kind.
VALUE Scalar of the same type as ATOM. If the kind
is different, the value is converted to the
kind of ATOM.
STAT (optional) Scalar default-kind integer
variable.
_Example_:
program atomic
use iso_fortran_env
integer(atomic_int_kind) :: atom[*]
call atomic_xor (atom[1], int(b'10100011101'))
end program atomic
_See also_:
*note ATOMIC_DEFINE::, *note ATOMIC_FETCH_XOR::, *note
ISO_FORTRAN_ENV::, *note ATOMIC_ADD::, *note ATOMIC_OR::, *note
ATOMIC_XOR::

File: gfortran.info, Node: BACKTRACE, Next: BESSEL_J0, Prev: ATOMIC_XOR, Up: Intrinsic Procedures
9.39 `BACKTRACE' -- Show a backtrace
====================================
_Description_:
`BACKTRACE' shows a backtrace at an arbitrary place in user code.
Program execution continues normally afterwards. The backtrace
information is printed to the unit corresponding to `ERROR_UNIT'
in `ISO_FORTRAN_ENV'.
_Standard_:
GNU Extension
_Class_:
Subroutine
_Syntax_:
`CALL BACKTRACE'
_Arguments_:
None
_See also_:
*note ABORT::

File: gfortran.info, Node: BESSEL_J0, Next: BESSEL_J1, Prev: BACKTRACE, Up: Intrinsic Procedures
9.40 `BESSEL_J0' -- Bessel function of the first kind of order 0
================================================================
_Description_:
`BESSEL_J0(X)' computes the Bessel function of the first kind of
order 0 of X. This function is available under the name `BESJ0' as
a GNU extension.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = BESSEL_J0(X)'
_Arguments_:
X The type shall be `REAL'.
_Return value_:
The return value is of type `REAL' and lies in the range -
0.4027... \leq Bessel (0,x) \leq 1. It has the same kind as X.
_Example_:
program test_besj0
real(8) :: x = 0.0_8
x = bessel_j0(x)
end program test_besj0
_Specific names_:
Name Argument Return type Standard
`DBESJ0(X)' `REAL(8) X' `REAL(8)' GNU extension

File: gfortran.info, Node: BESSEL_J1, Next: BESSEL_JN, Prev: BESSEL_J0, Up: Intrinsic Procedures
9.41 `BESSEL_J1' -- Bessel function of the first kind of order 1
================================================================
_Description_:
`BESSEL_J1(X)' computes the Bessel function of the first kind of
order 1 of X. This function is available under the name `BESJ1' as
a GNU extension.
_Standard_:
Fortran 2008
_Class_:
Elemental function
_Syntax_:
`RESULT = BESSEL_J1(X)'
_Arguments_:
X The type shall be `REAL'.
_Return value_:
The return value is of type `REAL' and lies in the range -
0.5818... \leq Bessel (0,x) \leq 0.5818 . It has the same kind as
X.
_Example_:
program test_besj1
real(8) :: x = 1.0_8
x = bessel_j1(x)
end program test_besj1
_Specific names_:
Name Argument Return type Standard
`DBESJ1(X)' `REAL(8) X' `REAL(8)' GNU extension

File: gfortran.info, Node: BESSEL_JN, Next: BESSEL_Y0, Prev: BESSEL_J1, Up: Intrinsic Procedures
9.42 `BESSEL_JN' -- Bessel function of the first kind
=====================================================
_Description_:
`BESSEL_JN(N, X)' computes the Bessel function of the first kind of
order N of X. This function is available under the name `BESJN' as
a GNU extension. If N and X are arrays, their ranks and shapes
shall conform.
`BESSEL_JN(N1, N2, X)' returns an array with the Bessel functions
of the first kind of the orders N1 to N2.
_Standard_:
Fortran 2008 and later, negative N is allowed as GNU extension
_Class_:
Elemental function, except for the transformational function
`BESSEL_JN(N1, N2, X)'
_Syntax_:
`RESULT = BESSEL_JN(N, X)'
`RESULT = BESSEL_JN(N1, N2, X)'
_Arguments_:
N Shall be a scalar or an array of type
`INTEGER'.
N1 Shall be a non-negative scalar of type
`INTEGER'.
N2 Shall be a non-negative scalar of type
`INTEGER'.
X Shall be a scalar or an array of type `REAL';
for `BESSEL_JN(N1, N2, X)' it shall be scalar.
_Return value_:
The return value is a scalar of type `REAL'. It has the same kind
as X.
_Note_:
The transformational function uses a recurrence algorithm which
might, for some values of X, lead to different results than calls
to the elemental function.
_Example_:
program test_besjn
real(8) :: x = 1.0_8
x = bessel_jn(5,x)
end program test_besjn
_Specific names_:
Name Argument Return type Standard
`DBESJN(N, `INTEGER N' `REAL(8)' GNU extension
X)'
`REAL(8) X'

File: gfortran.info, Node: BESSEL_Y0, Next: BESSEL_Y1, Prev: BESSEL_JN, Up: Intrinsic Procedures
9.43 `BESSEL_Y0' -- Bessel function of the second kind of order 0
=================================================================
_Description_:
`BESSEL_Y0(X)' computes the Bessel function of the second kind of
order 0 of X. This function is available under the name `BESY0' as
a GNU extension.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = BESSEL_Y0(X)'
_Arguments_:
X The type shall be `REAL'.
_Return value_:
The return value is of type `REAL'. It has the same kind as X.
_Example_:
program test_besy0
real(8) :: x = 0.0_8
x = bessel_y0(x)
end program test_besy0
_Specific names_:
Name Argument Return type Standard
`DBESY0(X)' `REAL(8) X' `REAL(8)' GNU extension

File: gfortran.info, Node: BESSEL_Y1, Next: BESSEL_YN, Prev: BESSEL_Y0, Up: Intrinsic Procedures
9.44 `BESSEL_Y1' -- Bessel function of the second kind of order 1
=================================================================
_Description_:
`BESSEL_Y1(X)' computes the Bessel function of the second kind of
order 1 of X. This function is available under the name `BESY1' as
a GNU extension.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = BESSEL_Y1(X)'
_Arguments_:
X The type shall be `REAL'.
_Return value_:
The return value is of type `REAL'. It has the same kind as X.
_Example_:
program test_besy1
real(8) :: x = 1.0_8
x = bessel_y1(x)
end program test_besy1
_Specific names_:
Name Argument Return type Standard
`DBESY1(X)' `REAL(8) X' `REAL(8)' GNU extension

File: gfortran.info, Node: BESSEL_YN, Next: BGE, Prev: BESSEL_Y1, Up: Intrinsic Procedures
9.45 `BESSEL_YN' -- Bessel function of the second kind
======================================================
_Description_:
`BESSEL_YN(N, X)' computes the Bessel function of the second kind
of order N of X. This function is available under the name `BESYN'
as a GNU extension. If N and X are arrays, their ranks and shapes
shall conform.
`BESSEL_YN(N1, N2, X)' returns an array with the Bessel functions
of the first kind of the orders N1 to N2.
_Standard_:
Fortran 2008 and later, negative N is allowed as GNU extension
_Class_:
Elemental function, except for the transformational function
`BESSEL_YN(N1, N2, X)'
_Syntax_:
`RESULT = BESSEL_YN(N, X)'
`RESULT = BESSEL_YN(N1, N2, X)'
_Arguments_:
N Shall be a scalar or an array of type
`INTEGER' .
N1 Shall be a non-negative scalar of type
`INTEGER'.
N2 Shall be a non-negative scalar of type
`INTEGER'.
X Shall be a scalar or an array of type `REAL';
for `BESSEL_YN(N1, N2, X)' it shall be scalar.
_Return value_:
The return value is a scalar of type `REAL'. It has the same kind
as X.
_Note_:
The transformational function uses a recurrence algorithm which
might, for some values of X, lead to different results than calls
to the elemental function.
_Example_:
program test_besyn
real(8) :: x = 1.0_8
x = bessel_yn(5,x)
end program test_besyn
_Specific names_:
Name Argument Return type Standard
`DBESYN(N,X)' `INTEGER N' `REAL(8)' GNU extension
`REAL(8) X'

File: gfortran.info, Node: BGE, Next: BGT, Prev: BESSEL_YN, Up: Intrinsic Procedures
9.46 `BGE' -- Bitwise greater than or equal to
==============================================
_Description_:
Determines whether an integral is a bitwise greater than or equal
to another.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = BGE(I, J)'
_Arguments_:
I Shall be of `INTEGER' type.
J Shall be of `INTEGER' type, and of the same
kind as I.
_Return value_:
The return value is of type `LOGICAL' and of the default kind.
_See also_:
*note BGT::, *note BLE::, *note BLT::

File: gfortran.info, Node: BGT, Next: BIT_SIZE, Prev: BGE, Up: Intrinsic Procedures
9.47 `BGT' -- Bitwise greater than
==================================
_Description_:
Determines whether an integral is a bitwise greater than another.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = BGT(I, J)'
_Arguments_:
I Shall be of `INTEGER' type.
J Shall be of `INTEGER' type, and of the same
kind as I.
_Return value_:
The return value is of type `LOGICAL' and of the default kind.
_See also_:
*note BGE::, *note BLE::, *note BLT::

File: gfortran.info, Node: BIT_SIZE, Next: BLE, Prev: BGT, Up: Intrinsic Procedures
9.48 `BIT_SIZE' -- Bit size inquiry function
============================================
_Description_:
`BIT_SIZE(I)' returns the number of bits (integer precision plus
sign bit) represented by the type of I. The result of
`BIT_SIZE(I)' is independent of the actual value of I.
_Standard_:
Fortran 95 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = BIT_SIZE(I)'
_Arguments_:
I The type shall be `INTEGER'.
_Return value_:
The return value is of type `INTEGER'
_Example_:
program test_bit_size
integer :: i = 123
integer :: size
size = bit_size(i)
print *, size
end program test_bit_size

File: gfortran.info, Node: BLE, Next: BLT, Prev: BIT_SIZE, Up: Intrinsic Procedures
9.49 `BLE' -- Bitwise less than or equal to
===========================================
_Description_:
Determines whether an integral is a bitwise less than or equal to
another.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = BLE(I, J)'
_Arguments_:
I Shall be of `INTEGER' type.
J Shall be of `INTEGER' type, and of the same
kind as I.
_Return value_:
The return value is of type `LOGICAL' and of the default kind.
_See also_:
*note BGT::, *note BGE::, *note BLT::

File: gfortran.info, Node: BLT, Next: BTEST, Prev: BLE, Up: Intrinsic Procedures
9.50 `BLT' -- Bitwise less than
===============================
_Description_:
Determines whether an integral is a bitwise less than another.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = BLT(I, J)'
_Arguments_:
I Shall be of `INTEGER' type.
J Shall be of `INTEGER' type, and of the same
kind as I.
_Return value_:
The return value is of type `LOGICAL' and of the default kind.
_See also_:
*note BGE::, *note BGT::, *note BLE::

File: gfortran.info, Node: BTEST, Next: C_ASSOCIATED, Prev: BLT, Up: Intrinsic Procedures
9.51 `BTEST' -- Bit test function
=================================
_Description_:
`BTEST(I,POS)' returns logical `.TRUE.' if the bit at POS in I is
set. The counting of the bits starts at 0.
_Standard_:
Fortran 95 and later, has overloads that are GNU extensions
_Class_:
Elemental function
_Syntax_:
`RESULT = BTEST(I, POS)'
_Arguments_:
I The type shall be `INTEGER'.
POS The type shall be `INTEGER'.
_Return value_:
The return value is of type `LOGICAL'
_Example_:
program test_btest
integer :: i = 32768 + 1024 + 64
integer :: pos
logical :: bool
do pos=0,16
bool = btest(i, pos)
print *, pos, bool
end do
end program test_btest
_Specific names_:
Name Argument Return type Standard
`BTEST(I,POS)'`INTEGER `LOGICAL' F95 and later
I,POS'
`BBTEST(I,POS)'`INTEGER(1) `LOGICAL(1)' GNU extension
I,POS'
`BITEST(I,POS)'`INTEGER(2) `LOGICAL(2)' GNU extension
I,POS'
`BJTEST(I,POS)'`INTEGER(4) `LOGICAL(4)' GNU extension
I,POS'
`BKTEST(I,POS)'`INTEGER(8) `LOGICAL(8)' GNU extension
I,POS'

File: gfortran.info, Node: C_ASSOCIATED, Next: C_F_POINTER, Prev: BTEST, Up: Intrinsic Procedures
9.52 `C_ASSOCIATED' -- Status of a C pointer
============================================
_Description_:
`C_ASSOCIATED(c_ptr_1[, c_ptr_2])' determines the status of the C
pointer C_PTR_1 or if C_PTR_1 is associated with the target
C_PTR_2.
_Standard_:
Fortran 2003 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = C_ASSOCIATED(c_ptr_1[, c_ptr_2])'
_Arguments_:
C_PTR_1 Scalar of the type `C_PTR' or `C_FUNPTR'.
C_PTR_2 (Optional) Scalar of the same type as C_PTR_1.
_Return value_:
The return value is of type `LOGICAL'; it is `.false.' if either
C_PTR_1 is a C NULL pointer or if C_PTR1 and C_PTR_2 point to
different addresses.
_Example_:
subroutine association_test(a,b)
use iso_c_binding, only: c_associated, c_loc, c_ptr
implicit none
real, pointer :: a
type(c_ptr) :: b
if(c_associated(b, c_loc(a))) &
stop 'b and a do not point to same target'
end subroutine association_test
_See also_:
*note C_LOC::, *note C_FUNLOC::

File: gfortran.info, Node: C_F_POINTER, Next: C_F_PROCPOINTER, Prev: C_ASSOCIATED, Up: Intrinsic Procedures
9.53 `C_F_POINTER' -- Convert C into Fortran pointer
====================================================
_Description_:
`C_F_POINTER(CPTR, FPTR[, SHAPE])' assigns the target of the C
pointer CPTR to the Fortran pointer FPTR and specifies its shape.
_Standard_:
Fortran 2003 and later
_Class_:
Subroutine
_Syntax_:
`CALL C_F_POINTER(CPTR, FPTR[, SHAPE])'
_Arguments_:
CPTR scalar of the type `C_PTR'. It is `INTENT(IN)'.
FPTR pointer interoperable with CPTR. It is
`INTENT(OUT)'.
SHAPE (Optional) Rank-one array of type `INTEGER'
with `INTENT(IN)'. It shall be present if and
only if FPTR is an array. The size must be
equal to the rank of FPTR.
_Example_:
program main
use iso_c_binding
implicit none
interface
subroutine my_routine(p) bind(c,name='myC_func')
import :: c_ptr
type(c_ptr), intent(out) :: p
end subroutine
end interface
type(c_ptr) :: cptr
real,pointer :: a(:)
call my_routine(cptr)
call c_f_pointer(cptr, a, [12])
end program main
_See also_:
*note C_LOC::, *note C_F_PROCPOINTER::

File: gfortran.info, Node: C_F_PROCPOINTER, Next: C_FUNLOC, Prev: C_F_POINTER, Up: Intrinsic Procedures
9.54 `C_F_PROCPOINTER' -- Convert C into Fortran procedure pointer
==================================================================
_Description_:
`C_F_PROCPOINTER(CPTR, FPTR)' Assign the target of the C function
pointer CPTR to the Fortran procedure pointer FPTR.
_Standard_:
Fortran 2003 and later
_Class_:
Subroutine
_Syntax_:
`CALL C_F_PROCPOINTER(cptr, fptr)'
_Arguments_:
CPTR scalar of the type `C_FUNPTR'. It is
`INTENT(IN)'.
FPTR procedure pointer interoperable with CPTR. It
is `INTENT(OUT)'.
_Example_:
program main
use iso_c_binding
implicit none
abstract interface
function func(a)
import :: c_float
real(c_float), intent(in) :: a
real(c_float) :: func
end function
end interface
interface
function getIterFunc() bind(c,name="getIterFunc")
import :: c_funptr
type(c_funptr) :: getIterFunc
end function
end interface
type(c_funptr) :: cfunptr
procedure(func), pointer :: myFunc
cfunptr = getIterFunc()
call c_f_procpointer(cfunptr, myFunc)
end program main
_See also_:
*note C_LOC::, *note C_F_POINTER::

File: gfortran.info, Node: C_FUNLOC, Next: C_LOC, Prev: C_F_PROCPOINTER, Up: Intrinsic Procedures
9.55 `C_FUNLOC' -- Obtain the C address of a procedure
======================================================
_Description_:
`C_FUNLOC(x)' determines the C address of the argument.
_Standard_:
Fortran 2003 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = C_FUNLOC(x)'
_Arguments_:
X Interoperable function or pointer to such
function.
_Return value_:
The return value is of type `C_FUNPTR' and contains the C address
of the argument.
_Example_:
module x
use iso_c_binding
implicit none
contains
subroutine sub(a) bind(c)
real(c_float) :: a
a = sqrt(a)+5.0
end subroutine sub
end module x
program main
use iso_c_binding
use x
implicit none
interface
subroutine my_routine(p) bind(c,name='myC_func')
import :: c_funptr
type(c_funptr), intent(in) :: p
end subroutine
end interface
call my_routine(c_funloc(sub))
end program main
_See also_:
*note C_ASSOCIATED::, *note C_LOC::, *note C_F_POINTER::, *note
C_F_PROCPOINTER::

File: gfortran.info, Node: C_LOC, Next: C_SIZEOF, Prev: C_FUNLOC, Up: Intrinsic Procedures
9.56 `C_LOC' -- Obtain the C address of an object
=================================================
_Description_:
`C_LOC(X)' determines the C address of the argument.
_Standard_:
Fortran 2003 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = C_LOC(X)'
_Arguments_:
X Shall have either the POINTER or TARGET
attribute. It shall not be a coindexed object. It
shall either be a variable with interoperable
type and kind type parameters, or be a scalar,
nonpolymorphic variable with no length type
parameters.
_Return value_:
The return value is of type `C_PTR' and contains the C address of
the argument.
_Example_:
subroutine association_test(a,b)
use iso_c_binding, only: c_associated, c_loc, c_ptr
implicit none
real, pointer :: a
type(c_ptr) :: b
if(c_associated(b, c_loc(a))) &
stop 'b and a do not point to same target'
end subroutine association_test
_See also_:
*note C_ASSOCIATED::, *note C_FUNLOC::, *note C_F_POINTER::, *note
C_F_PROCPOINTER::

File: gfortran.info, Node: C_SIZEOF, Next: CEILING, Prev: C_LOC, Up: Intrinsic Procedures
9.57 `C_SIZEOF' -- Size in bytes of an expression
=================================================
_Description_:
`C_SIZEOF(X)' calculates the number of bytes of storage the
expression `X' occupies.
_Standard_:
Fortran 2008
_Class_:
Inquiry function of the module `ISO_C_BINDING'
_Syntax_:
`N = C_SIZEOF(X)'
_Arguments_:
X The argument shall be an interoperable data
entity.
_Return value_:
The return value is of type integer and of the system-dependent
kind `C_SIZE_T' (from the `ISO_C_BINDING' module). Its value is the
number of bytes occupied by the argument. If the argument has the
`POINTER' attribute, the number of bytes of the storage area
pointed to is returned. If the argument is of a derived type with
`POINTER' or `ALLOCATABLE' components, the return value does not
account for the sizes of the data pointed to by these components.
_Example_:
use iso_c_binding
integer(c_int) :: i
real(c_float) :: r, s(5)
print *, (c_sizeof(s)/c_sizeof(r) == 5)
end
The example will print `.TRUE.' unless you are using a platform
where default `REAL' variables are unusually padded.
_See also_:
*note SIZEOF::, *note STORAGE_SIZE::

File: gfortran.info, Node: CEILING, Next: CHAR, Prev: C_SIZEOF, Up: Intrinsic Procedures
9.58 `CEILING' -- Integer ceiling function
==========================================
_Description_:
`CEILING(A)' returns the least integer greater than or equal to A.
_Standard_:
Fortran 95 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = CEILING(A [, KIND])'
_Arguments_:
A The type shall be `REAL'.
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
_Return value_:
The return value is of type `INTEGER(KIND)' if KIND is present and
a default-kind `INTEGER' otherwise.
_Example_:
program test_ceiling
real :: x = 63.29
real :: y = -63.59
print *, ceiling(x) ! returns 64
print *, ceiling(y) ! returns -63
end program test_ceiling
_See also_:
*note FLOOR::, *note NINT::

File: gfortran.info, Node: CHAR, Next: CHDIR, Prev: CEILING, Up: Intrinsic Procedures
9.59 `CHAR' -- Character conversion function
============================================
_Description_:
`CHAR(I [, KIND])' returns the character represented by the
integer I.
_Standard_:
Fortran 77 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = CHAR(I [, KIND])'
_Arguments_:
I The type shall be `INTEGER'.
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
_Return value_:
The return value is of type `CHARACTER(1)'
_Example_:
program test_char
integer :: i = 74
character(1) :: c
c = char(i)
print *, i, c ! returns 'J'
end program test_char
_Specific names_:
Name Argument Return type Standard
`CHAR(I)' `INTEGER I' `CHARACTER(LEN=1)'F77 and later
_Note_:
See *note ICHAR:: for a discussion of converting between numerical
values and formatted string representations.
_See also_:
*note ACHAR::, *note IACHAR::, *note ICHAR::

File: gfortran.info, Node: CHDIR, Next: CHMOD, Prev: CHAR, Up: Intrinsic Procedures
9.60 `CHDIR' -- Change working directory
========================================
_Description_:
Change current working directory to a specified path.
This intrinsic is provided in both subroutine and function forms;
however, only one form can be used in any given program unit.
_Standard_:
GNU extension
_Class_:
Subroutine, function
_Syntax_:
`CALL CHDIR(NAME [, STATUS])'
`STATUS = CHDIR(NAME)'
_Arguments_:
NAME The type shall be `CHARACTER' of default kind
and shall specify a valid path within the file
system.
STATUS (Optional) `INTEGER' status flag of the default
kind. Returns 0 on success, and a system
specific and nonzero error code otherwise.
_Example_:
PROGRAM test_chdir
CHARACTER(len=255) :: path
CALL getcwd(path)
WRITE(*,*) TRIM(path)
CALL chdir("/tmp")
CALL getcwd(path)
WRITE(*,*) TRIM(path)
END PROGRAM
_See also_:
*note GETCWD::

File: gfortran.info, Node: CHMOD, Next: CMPLX, Prev: CHDIR, Up: Intrinsic Procedures
9.61 `CHMOD' -- Change access permissions of files
==================================================
_Description_:
`CHMOD' changes the permissions of a file.
This intrinsic is provided in both subroutine and function forms;
however, only one form can be used in any given program unit.
_Standard_:
GNU extension
_Class_:
Subroutine, function
_Syntax_:
`CALL CHMOD(NAME, MODE[, STATUS])'
`STATUS = CHMOD(NAME, MODE)'
_Arguments_:
NAME Scalar `CHARACTER' of default kind with the
file name. Trailing blanks are ignored unless
the character `achar(0)' is present, then all
characters up to and excluding `achar(0)' are
used as the file name.
MODE Scalar `CHARACTER' of default kind giving the
file permission. MODE uses the same syntax as
the `chmod' utility as defined by the POSIX
standard. The argument shall either be a
string of a nonnegative octal number or a
symbolic mode.
STATUS (optional) scalar `INTEGER', which is `0' on
success and nonzero otherwise.
_Return value_:
In either syntax, STATUS is set to `0' on success and nonzero
otherwise.
_Example_:
`CHMOD' as subroutine
program chmod_test
implicit none
integer :: status
call chmod('test.dat','u+x',status)
print *, 'Status: ', status
end program chmod_test
`CHMOD' as function:
program chmod_test
implicit none
integer :: status
status = chmod('test.dat','u+x')
print *, 'Status: ', status
end program chmod_test

File: gfortran.info, Node: CMPLX, Next: CO_BROADCAST, Prev: CHMOD, Up: Intrinsic Procedures
9.62 `CMPLX' -- Complex conversion function
===========================================
_Description_:
`CMPLX(X [, Y [, KIND]])' returns a complex number where X is
converted to the real component. If Y is present it is converted
to the imaginary component. If Y is not present then the
imaginary component is set to 0.0. If X is complex then Y must
not be present.
_Standard_:
Fortran 77 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = CMPLX(X [, Y [, KIND]])'
_Arguments_:
X The type may be `INTEGER', `REAL', or
`COMPLEX'.
Y (Optional; only allowed if X is not
`COMPLEX'.) May be `INTEGER' or `REAL'.
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
_Return value_:
The return value is of `COMPLEX' type, with a kind equal to KIND
if it is specified. If KIND is not specified, the result is of
the default `COMPLEX' kind, regardless of the kinds of X and Y.
_Example_:
program test_cmplx
integer :: i = 42
real :: x = 3.14
complex :: z
z = cmplx(i, x)
print *, z, cmplx(x)
end program test_cmplx
_See also_:
*note COMPLEX::

File: gfortran.info, Node: CO_BROADCAST, Next: CO_MAX, Prev: CMPLX, Up: Intrinsic Procedures
9.63 `CO_BROADCAST' -- Copy a value to all images the current set of images
===========================================================================
_Description_:
`CO_BROADCAST' copies the value of argument A on the image with
image index `SOURCE_IMAGE' to all images in the current team. A
becomes defined as if by intrinsic assignment. If the execution
was successful and STAT is present, it is assigned the value zero.
If the execution failed, STAT gets assigned a nonzero value and,
if present, ERRMSG gets assigned a value describing the occurred
error.
_Standard_:
Technical Specification (TS) 18508 or later
_Class_:
Collective subroutine
_Syntax_:
`CALL CO_BROADCAST(A, SOURCE_IMAGE [, STAT, ERRMSG])'
_Arguments_:
A INTENT(INOUT) argument; shall have the same
dynamic type and type paramters on all images
of the current team. If it is an array, it
shall have the same shape on all images.
SOURCE_IMAGEa scalar integer expression. It shall have
the same the same value on all images and
refer to an image of the current team.
STAT (optional) a scalar integer variable
ERRMSG (optional) a scalar character variable
_Example_:
program test
integer :: val(3)
if (this_image() == 1) then
val = [1, 5, 3]
end if
call co_broadcast (val, source_image=1)
print *, this_image, ":", val
end program test
_See also_:
*note CO_MAX::, *note CO_MIN::, *note CO_SUM::, *note CO_REDUCE::

File: gfortran.info, Node: CO_MAX, Next: CO_MIN, Prev: CO_BROADCAST, Up: Intrinsic Procedures
9.64 `CO_MAX' -- Maximal value on the current set of images
===========================================================
_Description_:
`CO_MAX' determines element-wise the maximal value of A on all
images of the current team. If RESULT_IMAGE is present, the
maximum values are returned in A on the specified image only and
the value of A on the other images become undefined. If
RESULT_IMAGE is not present, the value is returned on all images.
If the execution was successful and STAT is present, it is
assigned the value zero. If the execution failed, STAT gets
assigned a nonzero value and, if present, ERRMSG gets assigned a
value describing the occurred error.
_Standard_:
Technical Specification (TS) 18508 or later
_Class_:
Collective subroutine
_Syntax_:
`CALL CO_MAX(A [, RESULT_IMAGE, STAT, ERRMSG])'
_Arguments_:
A shall be an integer, real or character
variable, which has the same type and type
parameters on all images of the team.
RESULT_IMAGE(optional) a scalar integer expression; if
present, it shall have the same the same value
on all images and refer to an image of the
current team.
STAT (optional) a scalar integer variable
ERRMSG (optional) a scalar character variable
_Example_:
program test
integer :: val
val = this_image ()
call co_max (val, result_image=1)
if (this_image() == 1) then
write(*,*) "Maximal value", val ! prints num_images()
end if
end program test
_See also_:
*note CO_MIN::, *note CO_SUM::, *note CO_REDUCE::, *note
CO_BROADCAST::

File: gfortran.info, Node: CO_MIN, Next: CO_REDUCE, Prev: CO_MAX, Up: Intrinsic Procedures
9.65 `CO_MIN' -- Minimal value on the current set of images
===========================================================
_Description_:
`CO_MIN' determines element-wise the minimal value of A on all
images of the current team. If RESULT_IMAGE is present, the
minimal values are returned in A on the specified image only and
the value of A on the other images become undefined. If
RESULT_IMAGE is not present, the value is returned on all images.
If the execution was successful and STAT is present, it is
assigned the value zero. If the execution failed, STAT gets
assigned a nonzero value and, if present, ERRMSG gets assigned a
value describing the occurred error.
_Standard_:
Technical Specification (TS) 18508 or later
_Class_:
Collective subroutine
_Syntax_:
`CALL CO_MIN(A [, RESULT_IMAGE, STAT, ERRMSG])'
_Arguments_:
A shall be an integer, real or character
variable, which has the same type and type
parameters on all images of the team.
RESULT_IMAGE(optional) a scalar integer expression; if
present, it shall have the same the same value
on all images and refer to an image of the
current team.
STAT (optional) a scalar integer variable
ERRMSG (optional) a scalar character variable
_Example_:
program test
integer :: val
val = this_image ()
call co_min (val, result_image=1)
if (this_image() == 1) then
write(*,*) "Minimal value", val ! prints 1
end if
end program test
_See also_:
*note CO_MAX::, *note CO_SUM::, *note CO_REDUCE::, *note
CO_BROADCAST::

File: gfortran.info, Node: CO_REDUCE, Next: CO_SUM, Prev: CO_MIN, Up: Intrinsic Procedures
9.66 `CO_REDUCE' -- Reduction of values on the current set of images
====================================================================
_Description_:
`CO_REDUCE' determines element-wise the reduction of the value of A
on all images of the current team. The pure function passed as
OPERATOR is used to pairwise reduce the values of A by passing
either the value of A of different images or the result values of
such a reduction as argument. If A is an array, the deduction is
done element wise. If RESULT_IMAGE is present, the result values
are returned in A on the specified image only and the value of A
on the other images become undefined. If RESULT_IMAGE is not
present, the value is returned on all images. If the execution
was successful and STAT is present, it is assigned the value zero.
If the execution failed, STAT gets assigned a nonzero value and,
if present, ERRMSG gets assigned a value describing the occurred
error.
_Standard_:
Technical Specification (TS) 18508 or later
_Class_:
Collective subroutine
_Syntax_:
`CALL CO_REDUCE(A, OPERATOR, [, RESULT_IMAGE, STAT, ERRMSG])'
_Arguments_:
A is an `INTENT(INOUT)' argument and shall be
nonpolymorphic. If it is allocatable, it shall
be allocated; if it is a pointer, it shall be
associated. A shall have the same type and
type parameters on all images of the team; if
it is an array, it shall have the same shape
on all images.
OPERATOR pure function with two scalar nonallocatable
arguments, which shall be nonpolymorphic and
have the same type and type parameters as A.
The function shall return a nonallocatable
scalar of the same type and type parameters as
A. The function shall be the same on all
images and with regards to the arguments
mathematically commutative and associative.
Note that OPERATOR may not be an elemental
function, unless it is an intrisic function.
RESULT_IMAGE(optional) a scalar integer expression; if
present, it shall have the same the same value
on all images and refer to an image of the
current team.
STAT (optional) a scalar integer variable
ERRMSG (optional) a scalar character variable
_Example_:
program test
integer :: val
val = this_image ()
call co_reduce (val, result_image=1, operator=myprod)
if (this_image() == 1) then
write(*,*) "Product value", val ! prints num_images() factorial
end if
contains
pure function myprod(a, b)
integer, value :: a, b
integer :: myprod
myprod = a * b
end function myprod
end program test
_Note_:
While the rules permit in principle an intrinsic function, none of
the intrinsics in the standard fulfill the criteria of having a
specific function, which takes two arguments of the same type and
returning that type as result.
_See also_:
*note CO_MIN::, *note CO_MAX::, *note CO_SUM::, *note
CO_BROADCAST::

File: gfortran.info, Node: CO_SUM, Next: COMMAND_ARGUMENT_COUNT, Prev: CO_REDUCE, Up: Intrinsic Procedures
9.67 `CO_SUM' -- Sum of values on the current set of images
===========================================================
_Description_:
`CO_SUM' sums up the values of each element of A on all images of
the current team. If RESULT_IMAGE is present, the summed-up
values are returned in A on the specified image only and the value
of A on the other images become undefined. If RESULT_IMAGE is not
present, the value is returned on all images. If the execution was
successful and STAT is present, it is assigned the value zero. If
the execution failed, STAT gets assigned a nonzero value and, if
present, ERRMSG gets assigned a value describing the occurred
error.
_Standard_:
Technical Specification (TS) 18508 or later
_Class_:
Collective subroutine
_Syntax_:
`CALL CO_MIN(A [, RESULT_IMAGE, STAT, ERRMSG])'
_Arguments_:
A shall be an integer, real or complex variable,
which has the same type and type parameters on
all images of the team.
RESULT_IMAGE(optional) a scalar integer expression; if
present, it shall have the same the same value
on all images and refer to an image of the
current team.
STAT (optional) a scalar integer variable
ERRMSG (optional) a scalar character variable
_Example_:
program test
integer :: val
val = this_image ()
call co_sum (val, result_image=1)
if (this_image() == 1) then
write(*,*) "The sum is ", val ! prints (n**2 + n)/2, with n = num_images()
end if
end program test
_See also_:
*note CO_MAX::, *note CO_MIN::, *note CO_REDUCE::, *note
CO_BROADCAST::

File: gfortran.info, Node: COMMAND_ARGUMENT_COUNT, Next: COMPILER_OPTIONS, Prev: CO_SUM, Up: Intrinsic Procedures
9.68 `COMMAND_ARGUMENT_COUNT' -- Get number of command line arguments
=====================================================================
_Description_:
`COMMAND_ARGUMENT_COUNT' returns the number of arguments passed on
the command line when the containing program was invoked.
_Standard_:
Fortran 2003 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = COMMAND_ARGUMENT_COUNT()'
_Arguments_:
None
_Return value_:
The return value is an `INTEGER' of default kind.
_Example_:
program test_command_argument_count
integer :: count
count = command_argument_count()
print *, count
end program test_command_argument_count
_See also_:
*note GET_COMMAND::, *note GET_COMMAND_ARGUMENT::

File: gfortran.info, Node: COMPILER_OPTIONS, Next: COMPILER_VERSION, Prev: COMMAND_ARGUMENT_COUNT, Up: Intrinsic Procedures
9.69 `COMPILER_OPTIONS' -- Options passed to the compiler
=========================================================
_Description_:
`COMPILER_OPTIONS' returns a string with the options used for
compiling.
_Standard_:
Fortran 2008
_Class_:
Inquiry function of the module `ISO_FORTRAN_ENV'
_Syntax_:
`STR = COMPILER_OPTIONS()'
_Arguments_:
None.
_Return value_:
The return value is a default-kind string with system-dependent
length. It contains the compiler flags used to compile the file,
which called the `COMPILER_OPTIONS' intrinsic.
_Example_:
use iso_fortran_env
print '(4a)', 'This file was compiled by ', &
compiler_version(), ' using the options ', &
compiler_options()
end
_See also_:
*note COMPILER_VERSION::, *note ISO_FORTRAN_ENV::

File: gfortran.info, Node: COMPILER_VERSION, Next: COMPLEX, Prev: COMPILER_OPTIONS, Up: Intrinsic Procedures
9.70 `COMPILER_VERSION' -- Compiler version string
==================================================
_Description_:
`COMPILER_VERSION' returns a string with the name and the version
of the compiler.
_Standard_:
Fortran 2008
_Class_:
Inquiry function of the module `ISO_FORTRAN_ENV'
_Syntax_:
`STR = COMPILER_VERSION()'
_Arguments_:
None.
_Return value_:
The return value is a default-kind string with system-dependent
length. It contains the name of the compiler and its version
number.
_Example_:
use iso_fortran_env
print '(4a)', 'This file was compiled by ', &
compiler_version(), ' using the options ', &
compiler_options()
end
_See also_:
*note COMPILER_OPTIONS::, *note ISO_FORTRAN_ENV::

File: gfortran.info, Node: COMPLEX, Next: CONJG, Prev: COMPILER_VERSION, Up: Intrinsic Procedures
9.71 `COMPLEX' -- Complex conversion function
=============================================
_Description_:
`COMPLEX(X, Y)' returns a complex number where X is converted to
the real component and Y is converted to the imaginary component.
_Standard_:
GNU extension
_Class_:
Elemental function
_Syntax_:
`RESULT = COMPLEX(X, Y)'
_Arguments_:
X The type may be `INTEGER' or `REAL'.
Y The type may be `INTEGER' or `REAL'.
_Return value_:
If X and Y are both of `INTEGER' type, then the return value is of
default `COMPLEX' type.
If X and Y are of `REAL' type, or one is of `REAL' type and one is
of `INTEGER' type, then the return value is of `COMPLEX' type with
a kind equal to that of the `REAL' argument with the highest
precision.
_Example_:
program test_complex
integer :: i = 42
real :: x = 3.14
print *, complex(i, x)
end program test_complex
_See also_:
*note CMPLX::

File: gfortran.info, Node: CONJG, Next: COS, Prev: COMPLEX, Up: Intrinsic Procedures
9.72 `CONJG' -- Complex conjugate function
==========================================
_Description_:
`CONJG(Z)' returns the conjugate of Z. If Z is `(x, y)' then the
result is `(x, -y)'
_Standard_:
Fortran 77 and later, has overloads that are GNU extensions
_Class_:
Elemental function
_Syntax_:
`Z = CONJG(Z)'
_Arguments_:
Z The type shall be `COMPLEX'.
_Return value_:
The return value is of type `COMPLEX'.
_Example_:
program test_conjg
complex :: z = (2.0, 3.0)
complex(8) :: dz = (2.71_8, -3.14_8)
z= conjg(z)
print *, z
dz = dconjg(dz)
print *, dz
end program test_conjg
_Specific names_:
Name Argument Return type Standard
`CONJG(Z)' `COMPLEX Z' `COMPLEX' GNU extension
`DCONJG(Z)' `COMPLEX(8) `COMPLEX(8)' GNU extension
Z'

File: gfortran.info, Node: COS, Next: COSD, Prev: CONJG, Up: Intrinsic Procedures
9.73 `COS' -- Cosine function
=============================
_Description_:
`COS(X)' computes the cosine of X.
_Standard_:
Fortran 77 and later, has overloads that are GNU extensions
_Class_:
Elemental function
_Syntax_:
`RESULT = COS(X)'
_Arguments_:
X The type shall be `REAL' or `COMPLEX'.
_Return value_:
The return value is of the same type and kind as X. The real part
of the result is in radians. If X is of the type `REAL', the
return value lies in the range -1 \leq \cos (x) \leq 1.
_Example_:
program test_cos
real :: x = 0.0
x = cos(x)
end program test_cos
_Specific names_:
Name Argument Return type Standard
`COS(X)' `REAL(4) X' `REAL(4)' Fortran 77 and
later
`DCOS(X)' `REAL(8) X' `REAL(8)' Fortran 77 and
later
`CCOS(X)' `COMPLEX(4) `COMPLEX(4)' Fortran 77 and
X' later
`ZCOS(X)' `COMPLEX(8) `COMPLEX(8)' GNU extension
X'
`CDCOS(X)' `COMPLEX(8) `COMPLEX(8)' GNU extension
X'
_See also_:
Inverse function: *note ACOS:: Degrees function: *note COSD::

File: gfortran.info, Node: COSD, Next: COSH, Prev: COS, Up: Intrinsic Procedures
9.74 `COSD' -- Cosine function, degrees
=======================================
_Description_:
`COSD(X)' computes the cosine of X in degrees.
This function is for compatibility only and should be avoided in
favor of standard constructs wherever possible.
_Standard_:
GNU Extension, enabled with `-fdec-math'.
_Class_:
Elemental function
_Syntax_:
`RESULT = COSD(X)'
_Arguments_:
X The type shall be `REAL' or `COMPLEX'.
_Return value_:
The return value is of the same type and kind as X. The real part
of the result is in degrees. If X is of the type `REAL', the
return value lies in the range -1 \leq \cosd (x) \leq 1.
_Example_:
program test_cosd
real :: x = 0.0
x = cosd(x)
end program test_cosd
_Specific names_:
Name Argument Return type Standard
`COSD(X)' `REAL(4) X' `REAL(4)' GNU Extension
`DCOSD(X)' `REAL(8) X' `REAL(8)' GNU Extension
`CCOSD(X)' `COMPLEX(4) `COMPLEX(4)' GNU Extension
X'
`ZCOSD(X)' `COMPLEX(8) `COMPLEX(8)' GNU extension
X'
`CDCOSD(X)' `COMPLEX(8) `COMPLEX(8)' GNU extension
X'
_See also_:
Inverse function: *note ACOSD:: Radians function: *note COS::

File: gfortran.info, Node: COSH, Next: COTAN, Prev: COSD, Up: Intrinsic Procedures
9.75 `COSH' -- Hyperbolic cosine function
=========================================
_Description_:
`COSH(X)' computes the hyperbolic cosine of X.
_Standard_:
Fortran 77 and later, for a complex argument Fortran 2008 or later
_Class_:
Elemental function
_Syntax_:
`X = COSH(X)'
_Arguments_:
X The type shall be `REAL' or `COMPLEX'.
_Return value_:
The return value has same type and kind as X. If X is complex, the
imaginary part of the result is in radians. If X is `REAL', the
return value has a lower bound of one, \cosh (x) \geq 1.
_Example_:
program test_cosh
real(8) :: x = 1.0_8
x = cosh(x)
end program test_cosh
_Specific names_:
Name Argument Return type Standard
`COSH(X)' `REAL(4) X' `REAL(4)' Fortran 77 and
later
`DCOSH(X)' `REAL(8) X' `REAL(8)' Fortran 77 and
later
_See also_:
Inverse function: *note ACOSH::

File: gfortran.info, Node: COTAN, Next: COTAND, Prev: COSH, Up: Intrinsic Procedures
9.76 `COTAN' -- Cotangent function
==================================
_Description_:
`COTAN(X)' computes the cotangent of X. Equivalent to `COS(x)'
divided by `SIN(x)', or `1 / TAN(x)'.
This function is for compatibility only and should be avoided in
favor of standard constructs wherever possible.
_Standard_:
GNU Extension, enabled with `-fdec-math'.
_Class_:
Elemental function
_Syntax_:
`RESULT = COTAN(X)'
_Arguments_:
X The type shall be `REAL' or `COMPLEX'.
_Return value_:
The return value has same type and kind as X, and its value is in
radians.
_Example_:
program test_cotan
real(8) :: x = 0.165_8
x = cotan(x)
end program test_cotan
_Specific names_:
Name Argument Return type Standard
`COTAN(X)' `REAL(4) X' `REAL(4)' GNU Extension
`DCOTAN(X)' `REAL(8) X' `REAL(8)' GNU Extension
_See also_:
Converse function: *note TAN:: Degrees function: *note COTAND::

File: gfortran.info, Node: COTAND, Next: COUNT, Prev: COTAN, Up: Intrinsic Procedures
9.77 `COTAND' -- Cotangent function, degrees
============================================
_Description_:
`COTAND(X)' computes the cotangent of X in degrees. Equivalent to
`COSD(x)' divided by `SIND(x)', or `1 / TAND(x)'.
_Standard_:
GNU Extension, enabled with `-fdec-math'.
This function is for compatibility only and should be avoided in
favor of standard constructs wherever possible.
_Class_:
Elemental function
_Syntax_:
`RESULT = COTAND(X)'
_Arguments_:
X The type shall be `REAL' or `COMPLEX'.
_Return value_:
The return value has same type and kind as X, and its value is in
degrees.
_Example_:
program test_cotand
real(8) :: x = 0.165_8
x = cotand(x)
end program test_cotand
_Specific names_:
Name Argument Return type Standard
`COTAND(X)' `REAL(4) X' `REAL(4)' GNU Extension
`DCOTAND(X)' `REAL(8) X' `REAL(8)' GNU Extension
_See also_:
Converse function: *note TAND:: Radians function: *note COTAN::

File: gfortran.info, Node: COUNT, Next: CPU_TIME, Prev: COTAND, Up: Intrinsic Procedures
9.78 `COUNT' -- Count function
==============================
_Description_:
Counts the number of `.TRUE.' elements in a logical MASK, or, if
the DIM argument is supplied, counts the number of elements along
each row of the array in the DIM direction. If the array has zero
size, or all of the elements of MASK are `.FALSE.', then the
result is `0'.
_Standard_:
Fortran 95 and later, with KIND argument Fortran 2003 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = COUNT(MASK [, DIM, KIND])'
_Arguments_:
MASK The type shall be `LOGICAL'.
DIM (Optional) The type shall be `INTEGER'.
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
_Return value_:
The return value is of type `INTEGER' and of kind KIND. If KIND is
absent, the return value is of default integer kind. If DIM is
present, the result is an array with a rank one less than the rank
of ARRAY, and a size corresponding to the shape of ARRAY with the
DIM dimension removed.
_Example_:
program test_count
integer, dimension(2,3) :: a, b
logical, dimension(2,3) :: mask
a = reshape( (/ 1, 2, 3, 4, 5, 6 /), (/ 2, 3 /))
b = reshape( (/ 0, 7, 3, 4, 5, 8 /), (/ 2, 3 /))
print '(3i3)', a(1,:)
print '(3i3)', a(2,:)
print *
print '(3i3)', b(1,:)
print '(3i3)', b(2,:)
print *
mask = a.ne.b
print '(3l3)', mask(1,:)
print '(3l3)', mask(2,:)
print *
print '(3i3)', count(mask)
print *
print '(3i3)', count(mask, 1)
print *
print '(3i3)', count(mask, 2)
end program test_count

File: gfortran.info, Node: CPU_TIME, Next: CSHIFT, Prev: COUNT, Up: Intrinsic Procedures
9.79 `CPU_TIME' -- CPU elapsed time in seconds
==============================================
_Description_:
Returns a `REAL' value representing the elapsed CPU time in
seconds. This is useful for testing segments of code to determine
execution time.
If a time source is available, time will be reported with
microsecond resolution. If no time source is available, TIME is
set to `-1.0'.
Note that TIME may contain a, system dependent, arbitrary offset
and may not start with `0.0'. For `CPU_TIME', the absolute value
is meaningless, only differences between subsequent calls to this
subroutine, as shown in the example below, should be used.
_Standard_:
Fortran 95 and later
_Class_:
Subroutine
_Syntax_:
`CALL CPU_TIME(TIME)'
_Arguments_:
TIME The type shall be `REAL' with `INTENT(OUT)'.
_Return value_:
None
_Example_:
program test_cpu_time
real :: start, finish
call cpu_time(start)
! put code to test here
call cpu_time(finish)
print '("Time = ",f6.3," seconds.")',finish-start
end program test_cpu_time
_See also_:
*note SYSTEM_CLOCK::, *note DATE_AND_TIME::

File: gfortran.info, Node: CSHIFT, Next: CTIME, Prev: CPU_TIME, Up: Intrinsic Procedures
9.80 `CSHIFT' -- Circular shift elements of an array
====================================================
_Description_:
`CSHIFT(ARRAY, SHIFT [, DIM])' performs a circular shift on
elements of ARRAY along the dimension of DIM. If DIM is omitted
it is taken to be `1'. DIM is a scalar of type `INTEGER' in the
range of 1 \leq DIM \leq n) where n is the rank of ARRAY. If the
rank of ARRAY is one, then all elements of ARRAY are shifted by
SHIFT places. If rank is greater than one, then all complete rank
one sections of ARRAY along the given dimension are shifted.
Elements shifted out one end of each rank one section are shifted
back in the other end.
_Standard_:
Fortran 95 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = CSHIFT(ARRAY, SHIFT [, DIM])'
_Arguments_:
ARRAY Shall be an array of any type.
SHIFT The type shall be `INTEGER'.
DIM The type shall be `INTEGER'.
_Return value_:
Returns an array of same type and rank as the ARRAY argument.
_Example_:
program test_cshift
integer, dimension(3,3) :: a
a = reshape( (/ 1, 2, 3, 4, 5, 6, 7, 8, 9 /), (/ 3, 3 /))
print '(3i3)', a(1,:)
print '(3i3)', a(2,:)
print '(3i3)', a(3,:)
a = cshift(a, SHIFT=(/1, 2, -1/), DIM=2)
print *
print '(3i3)', a(1,:)
print '(3i3)', a(2,:)
print '(3i3)', a(3,:)
end program test_cshift

File: gfortran.info, Node: CTIME, Next: DATE_AND_TIME, Prev: CSHIFT, Up: Intrinsic Procedures
9.81 `CTIME' -- Convert a time into a string
============================================
_Description_:
`CTIME' converts a system time value, such as returned by *note
TIME8::, to a string. The output will be of the form `Sat Aug 19
18:13:14 1995'.
This intrinsic is provided in both subroutine and function forms;
however, only one form can be used in any given program unit.
_Standard_:
GNU extension
_Class_:
Subroutine, function
_Syntax_:
`CALL CTIME(TIME, RESULT)'.
`RESULT = CTIME(TIME)'.
_Arguments_:
TIME The type shall be of type `INTEGER'.
RESULT The type shall be of type `CHARACTER' and of
default kind. It is an `INTENT(OUT)' argument.
If the length of this variable is too short
for the time and date string to fit
completely, it will be blank on procedure
return.
_Return value_:
The converted date and time as a string.
_Example_:
program test_ctime
integer(8) :: i
character(len=30) :: date
i = time8()
! Do something, main part of the program
call ctime(i,date)
print *, 'Program was started on ', date
end program test_ctime
_See Also_:
*note DATE_AND_TIME::, *note GMTIME::, *note LTIME::, *note
TIME::, *note TIME8::

File: gfortran.info, Node: DATE_AND_TIME, Next: DBLE, Prev: CTIME, Up: Intrinsic Procedures
9.82 `DATE_AND_TIME' -- Date and time subroutine
================================================
_Description_:
`DATE_AND_TIME(DATE, TIME, ZONE, VALUES)' gets the corresponding
date and time information from the real-time system clock. DATE is
`INTENT(OUT)' and has form ccyymmdd. TIME is `INTENT(OUT)' and
has form hhmmss.sss. ZONE is `INTENT(OUT)' and has form (+-)hhmm,
representing the difference with respect to Coordinated Universal
Time (UTC). Unavailable time and date parameters return blanks.
VALUES is `INTENT(OUT)' and provides the following:
`VALUE(1)': The year
`VALUE(2)': The month
`VALUE(3)': The day of the month
`VALUE(4)': Time difference with UTC
in minutes
`VALUE(5)': The hour of the day
`VALUE(6)': The minutes of the hour
`VALUE(7)': The seconds of the minute
`VALUE(8)': The milliseconds of the
second
_Standard_:
Fortran 95 and later
_Class_:
Subroutine
_Syntax_:
`CALL DATE_AND_TIME([DATE, TIME, ZONE, VALUES])'
_Arguments_:
DATE (Optional) The type shall be `CHARACTER(LEN=8)'
or larger, and of default kind.
TIME (Optional) The type shall be
`CHARACTER(LEN=10)' or larger, and of default
kind.
ZONE (Optional) The type shall be `CHARACTER(LEN=5)'
or larger, and of default kind.
VALUES (Optional) The type shall be `INTEGER(8)'.
_Return value_:
None
_Example_:
program test_time_and_date
character(8) :: date
character(10) :: time
character(5) :: zone
integer,dimension(8) :: values
! using keyword arguments
call date_and_time(date,time,zone,values)
call date_and_time(DATE=date,ZONE=zone)
call date_and_time(TIME=time)
call date_and_time(VALUES=values)
print '(a,2x,a,2x,a)', date, time, zone
print '(8i5)', values
end program test_time_and_date
_See also_:
*note CPU_TIME::, *note SYSTEM_CLOCK::

File: gfortran.info, Node: DBLE, Next: DCMPLX, Prev: DATE_AND_TIME, Up: Intrinsic Procedures
9.83 `DBLE' -- Double conversion function
=========================================
_Description_:
`DBLE(A)' Converts A to double precision real type.
_Standard_:
Fortran 77 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = DBLE(A)'
_Arguments_:
A The type shall be `INTEGER', `REAL', or
`COMPLEX'.
_Return value_:
The return value is of type double precision real.
_Example_:
program test_dble
real :: x = 2.18
integer :: i = 5
complex :: z = (2.3,1.14)
print *, dble(x), dble(i), dble(z)
end program test_dble
_See also_:
*note REAL::

File: gfortran.info, Node: DCMPLX, Next: DIGITS, Prev: DBLE, Up: Intrinsic Procedures
9.84 `DCMPLX' -- Double complex conversion function
===================================================
_Description_:
`DCMPLX(X [,Y])' returns a double complex number where X is
converted to the real component. If Y is present it is converted
to the imaginary component. If Y is not present then the
imaginary component is set to 0.0. If X is complex then Y must
not be present.
_Standard_:
GNU extension
_Class_:
Elemental function
_Syntax_:
`RESULT = DCMPLX(X [, Y])'
_Arguments_:
X The type may be `INTEGER', `REAL', or
`COMPLEX'.
Y (Optional if X is not `COMPLEX'.) May be
`INTEGER' or `REAL'.
_Return value_:
The return value is of type `COMPLEX(8)'
_Example_:
program test_dcmplx
integer :: i = 42
real :: x = 3.14
complex :: z
z = cmplx(i, x)
print *, dcmplx(i)
print *, dcmplx(x)
print *, dcmplx(z)
print *, dcmplx(x,i)
end program test_dcmplx

File: gfortran.info, Node: DIGITS, Next: DIM, Prev: DCMPLX, Up: Intrinsic Procedures
9.85 `DIGITS' -- Significant binary digits function
===================================================
_Description_:
`DIGITS(X)' returns the number of significant binary digits of the
internal model representation of X. For example, on a system
using a 32-bit floating point representation, a default real
number would likely return 24.
_Standard_:
Fortran 95 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = DIGITS(X)'
_Arguments_:
X The type may be `INTEGER' or `REAL'.
_Return value_:
The return value is of type `INTEGER'.
_Example_:
program test_digits
integer :: i = 12345
real :: x = 3.143
real(8) :: y = 2.33
print *, digits(i)
print *, digits(x)
print *, digits(y)
end program test_digits

File: gfortran.info, Node: DIM, Next: DOT_PRODUCT, Prev: DIGITS, Up: Intrinsic Procedures
9.86 `DIM' -- Positive difference
=================================
_Description_:
`DIM(X,Y)' returns the difference `X-Y' if the result is positive;
otherwise returns zero.
_Standard_:
Fortran 77 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = DIM(X, Y)'
_Arguments_:
X The type shall be `INTEGER' or `REAL'
Y The type shall be the same type and kind as X.
_Return value_:
The return value is of type `INTEGER' or `REAL'.
_Example_:
program test_dim
integer :: i
real(8) :: x
i = dim(4, 15)
x = dim(4.345_8, 2.111_8)
print *, i
print *, x
end program test_dim
_Specific names_:
Name Argument Return type Standard
`DIM(X,Y)' `REAL(4) X, `REAL(4)' Fortran 77 and
Y' later
`IDIM(X,Y)' `INTEGER(4) `INTEGER(4)' Fortran 77 and
X, Y' later
`DDIM(X,Y)' `REAL(8) X, `REAL(8)' Fortran 77 and
Y' later

File: gfortran.info, Node: DOT_PRODUCT, Next: DPROD, Prev: DIM, Up: Intrinsic Procedures
9.87 `DOT_PRODUCT' -- Dot product function
==========================================
_Description_:
`DOT_PRODUCT(VECTOR_A, VECTOR_B)' computes the dot product
multiplication of two vectors VECTOR_A and VECTOR_B. The two
vectors may be either numeric or logical and must be arrays of
rank one and of equal size. If the vectors are `INTEGER' or
`REAL', the result is `SUM(VECTOR_A*VECTOR_B)'. If the vectors are
`COMPLEX', the result is `SUM(CONJG(VECTOR_A)*VECTOR_B)'. If the
vectors are `LOGICAL', the result is `ANY(VECTOR_A .AND.
VECTOR_B)'.
_Standard_:
Fortran 95 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = DOT_PRODUCT(VECTOR_A, VECTOR_B)'
_Arguments_:
VECTOR_A The type shall be numeric or `LOGICAL', rank 1.
VECTOR_B The type shall be numeric if VECTOR_A is of
numeric type or `LOGICAL' if VECTOR_A is of
type `LOGICAL'. VECTOR_B shall be a rank-one
array.
_Return value_:
If the arguments are numeric, the return value is a scalar of
numeric type, `INTEGER', `REAL', or `COMPLEX'. If the arguments
are `LOGICAL', the return value is `.TRUE.' or `.FALSE.'.
_Example_:
program test_dot_prod
integer, dimension(3) :: a, b
a = (/ 1, 2, 3 /)
b = (/ 4, 5, 6 /)
print '(3i3)', a
print *
print '(3i3)', b
print *
print *, dot_product(a,b)
end program test_dot_prod

File: gfortran.info, Node: DPROD, Next: DREAL, Prev: DOT_PRODUCT, Up: Intrinsic Procedures
9.88 `DPROD' -- Double product function
=======================================
_Description_:
`DPROD(X,Y)' returns the product `X*Y'.
_Standard_:
Fortran 77 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = DPROD(X, Y)'
_Arguments_:
X The type shall be `REAL'.
Y The type shall be `REAL'.
_Return value_:
The return value is of type `REAL(8)'.
_Example_:
program test_dprod
real :: x = 5.2
real :: y = 2.3
real(8) :: d
d = dprod(x,y)
print *, d
end program test_dprod
_Specific names_:
Name Argument Return type Standard
`DPROD(X,Y)' `REAL(4) X, `REAL(8)' Fortran 77 and
Y' later

File: gfortran.info, Node: DREAL, Next: DSHIFTL, Prev: DPROD, Up: Intrinsic Procedures
9.89 `DREAL' -- Double real part function
=========================================
_Description_:
`DREAL(Z)' returns the real part of complex variable Z.
_Standard_:
GNU extension
_Class_:
Elemental function
_Syntax_:
`RESULT = DREAL(A)'
_Arguments_:
A The type shall be `COMPLEX(8)'.
_Return value_:
The return value is of type `REAL(8)'.
_Example_:
program test_dreal
complex(8) :: z = (1.3_8,7.2_8)
print *, dreal(z)
end program test_dreal
_See also_:
*note AIMAG::

File: gfortran.info, Node: DSHIFTL, Next: DSHIFTR, Prev: DREAL, Up: Intrinsic Procedures
9.90 `DSHIFTL' -- Combined left shift
=====================================
_Description_:
`DSHIFTL(I, J, SHIFT)' combines bits of I and J. The rightmost
SHIFT bits of the result are the leftmost SHIFT bits of J, and the
remaining bits are the rightmost bits of I.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = DSHIFTL(I, J, SHIFT)'
_Arguments_:
I Shall be of type `INTEGER' or a BOZ constant.
J Shall be of type `INTEGER' or a BOZ constant.
If both I and J have integer type, then they
shall have the same kind type parameter. I and
J shall not both be BOZ constants.
SHIFT Shall be of type `INTEGER'. It shall be
nonnegative. If I is not a BOZ constant, then
SHIFT shall be less than or equal to
`BIT_SIZE(I)'; otherwise, SHIFT shall be less
than or equal to `BIT_SIZE(J)'.
_Return value_:
If either I or J is a BOZ constant, it is first converted as if by
the intrinsic function `INT' to an integer type with the kind type
parameter of the other.
_See also_:
*note DSHIFTR::

File: gfortran.info, Node: DSHIFTR, Next: DTIME, Prev: DSHIFTL, Up: Intrinsic Procedures
9.91 `DSHIFTR' -- Combined right shift
======================================
_Description_:
`DSHIFTR(I, J, SHIFT)' combines bits of I and J. The leftmost
SHIFT bits of the result are the rightmost SHIFT bits of I, and
the remaining bits are the leftmost bits of J.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = DSHIFTR(I, J, SHIFT)'
_Arguments_:
I Shall be of type `INTEGER' or a BOZ constant.
J Shall be of type `INTEGER' or a BOZ constant.
If both I and J have integer type, then they
shall have the same kind type parameter. I and
J shall not both be BOZ constants.
SHIFT Shall be of type `INTEGER'. It shall be
nonnegative. If I is not a BOZ constant, then
SHIFT shall be less than or equal to
`BIT_SIZE(I)'; otherwise, SHIFT shall be less
than or equal to `BIT_SIZE(J)'.
_Return value_:
If either I or J is a BOZ constant, it is first converted as if by
the intrinsic function `INT' to an integer type with the kind type
parameter of the other.
_See also_:
*note DSHIFTL::

File: gfortran.info, Node: DTIME, Next: EOSHIFT, Prev: DSHIFTR, Up: Intrinsic Procedures
9.92 `DTIME' -- Execution time subroutine (or function)
=======================================================
_Description_:
`DTIME(VALUES, TIME)' initially returns the number of seconds of
runtime since the start of the process's execution in TIME. VALUES
returns the user and system components of this time in `VALUES(1)'
and `VALUES(2)' respectively. TIME is equal to `VALUES(1) +
VALUES(2)'.
Subsequent invocations of `DTIME' return values accumulated since
the previous invocation.
On some systems, the underlying timings are represented using
types with sufficiently small limits that overflows (wrap around)
are possible, such as 32-bit types. Therefore, the values returned
by this intrinsic might be, or become, negative, or numerically
less than previous values, during a single run of the compiled
program.
Please note, that this implementation is thread safe if used
within OpenMP directives, i.e., its state will be consistent while
called from multiple threads. However, if `DTIME' is called from
multiple threads, the result is still the time since the last
invocation. This may not give the intended results. If possible,
use `CPU_TIME' instead.
This intrinsic is provided in both subroutine and function forms;
however, only one form can be used in any given program unit.
VALUES and TIME are `INTENT(OUT)' and provide the following:
`VALUES(1)': User time in seconds.
`VALUES(2)': System time in seconds.
`TIME': Run time since start in
seconds.
_Standard_:
GNU extension
_Class_:
Subroutine, function
_Syntax_:
`CALL DTIME(VALUES, TIME)'.
`TIME = DTIME(VALUES)', (not recommended).
_Arguments_:
VALUES The type shall be `REAL(4), DIMENSION(2)'.
TIME The type shall be `REAL(4)'.
_Return value_:
Elapsed time in seconds since the last invocation or since the
start of program execution if not called before.
_Example_:
program test_dtime
integer(8) :: i, j
real, dimension(2) :: tarray
real :: result
call dtime(tarray, result)
print *, result
print *, tarray(1)
print *, tarray(2)
do i=1,100000000 ! Just a delay
j = i * i - i
end do
call dtime(tarray, result)
print *, result
print *, tarray(1)
print *, tarray(2)
end program test_dtime
_See also_:
*note CPU_TIME::

File: gfortran.info, Node: EOSHIFT, Next: EPSILON, Prev: DTIME, Up: Intrinsic Procedures
9.93 `EOSHIFT' -- End-off shift elements of an array
====================================================
_Description_:
`EOSHIFT(ARRAY, SHIFT[, BOUNDARY, DIM])' performs an end-off shift
on elements of ARRAY along the dimension of DIM. If DIM is
omitted it is taken to be `1'. DIM is a scalar of type `INTEGER'
in the range of 1 \leq DIM \leq n) where n is the rank of ARRAY.
If the rank of ARRAY is one, then all elements of ARRAY are
shifted by SHIFT places. If rank is greater than one, then all
complete rank one sections of ARRAY along the given dimension are
shifted. Elements shifted out one end of each rank one section
are dropped. If BOUNDARY is present then the corresponding value
of from BOUNDARY is copied back in the other end. If BOUNDARY is
not present then the following are copied in depending on the type
of ARRAY.
_Array _Boundary Value_
Type_
Numeric 0 of the type and kind of ARRAY.
Logical `.FALSE.'.
Character(LEN)LEN blanks.
_Standard_:
Fortran 95 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = EOSHIFT(ARRAY, SHIFT [, BOUNDARY, DIM])'
_Arguments_:
ARRAY May be any type, not scalar.
SHIFT The type shall be `INTEGER'.
BOUNDARY Same type as ARRAY.
DIM The type shall be `INTEGER'.
_Return value_:
Returns an array of same type and rank as the ARRAY argument.
_Example_:
program test_eoshift
integer, dimension(3,3) :: a
a = reshape( (/ 1, 2, 3, 4, 5, 6, 7, 8, 9 /), (/ 3, 3 /))
print '(3i3)', a(1,:)
print '(3i3)', a(2,:)
print '(3i3)', a(3,:)
a = EOSHIFT(a, SHIFT=(/1, 2, 1/), BOUNDARY=-5, DIM=2)
print *
print '(3i3)', a(1,:)
print '(3i3)', a(2,:)
print '(3i3)', a(3,:)
end program test_eoshift

File: gfortran.info, Node: EPSILON, Next: ERF, Prev: EOSHIFT, Up: Intrinsic Procedures
9.94 `EPSILON' -- Epsilon function
==================================
_Description_:
`EPSILON(X)' returns the smallest number E of the same kind as X
such that 1 + E > 1.
_Standard_:
Fortran 95 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = EPSILON(X)'
_Arguments_:
X The type shall be `REAL'.
_Return value_:
The return value is of same type as the argument.
_Example_:
program test_epsilon
real :: x = 3.143
real(8) :: y = 2.33
print *, EPSILON(x)
print *, EPSILON(y)
end program test_epsilon

File: gfortran.info, Node: ERF, Next: ERFC, Prev: EPSILON, Up: Intrinsic Procedures
9.95 `ERF' -- Error function
============================
_Description_:
`ERF(X)' computes the error function of X.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = ERF(X)'
_Arguments_:
X The type shall be `REAL'.
_Return value_:
The return value is of type `REAL', of the same kind as X and lies
in the range -1 \leq erf (x) \leq 1 .
_Example_:
program test_erf
real(8) :: x = 0.17_8
x = erf(x)
end program test_erf
_Specific names_:
Name Argument Return type Standard
`DERF(X)' `REAL(8) X' `REAL(8)' GNU extension

File: gfortran.info, Node: ERFC, Next: ERFC_SCALED, Prev: ERF, Up: Intrinsic Procedures
9.96 `ERFC' -- Error function
=============================
_Description_:
`ERFC(X)' computes the complementary error function of X.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = ERFC(X)'
_Arguments_:
X The type shall be `REAL'.
_Return value_:
The return value is of type `REAL' and of the same kind as X. It
lies in the range 0 \leq erfc (x) \leq 2 .
_Example_:
program test_erfc
real(8) :: x = 0.17_8
x = erfc(x)
end program test_erfc
_Specific names_:
Name Argument Return type Standard
`DERFC(X)' `REAL(8) X' `REAL(8)' GNU extension

File: gfortran.info, Node: ERFC_SCALED, Next: ETIME, Prev: ERFC, Up: Intrinsic Procedures
9.97 `ERFC_SCALED' -- Error function
====================================
_Description_:
`ERFC_SCALED(X)' computes the exponentially-scaled complementary
error function of X.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = ERFC_SCALED(X)'
_Arguments_:
X The type shall be `REAL'.
_Return value_:
The return value is of type `REAL' and of the same kind as X.
_Example_:
program test_erfc_scaled
real(8) :: x = 0.17_8
x = erfc_scaled(x)
end program test_erfc_scaled

File: gfortran.info, Node: ETIME, Next: EVENT_QUERY, Prev: ERFC_SCALED, Up: Intrinsic Procedures
9.98 `ETIME' -- Execution time subroutine (or function)
=======================================================
_Description_:
`ETIME(VALUES, TIME)' returns the number of seconds of runtime
since the start of the process's execution in TIME. VALUES
returns the user and system components of this time in `VALUES(1)'
and `VALUES(2)' respectively. TIME is equal to `VALUES(1) +
VALUES(2)'.
On some systems, the underlying timings are represented using
types with sufficiently small limits that overflows (wrap around)
are possible, such as 32-bit types. Therefore, the values returned
by this intrinsic might be, or become, negative, or numerically
less than previous values, during a single run of the compiled
program.
This intrinsic is provided in both subroutine and function forms;
however, only one form can be used in any given program unit.
VALUES and TIME are `INTENT(OUT)' and provide the following:
`VALUES(1)': User time in seconds.
`VALUES(2)': System time in seconds.
`TIME': Run time since start in seconds.
_Standard_:
GNU extension
_Class_:
Subroutine, function
_Syntax_:
`CALL ETIME(VALUES, TIME)'.
`TIME = ETIME(VALUES)', (not recommended).
_Arguments_:
VALUES The type shall be `REAL(4), DIMENSION(2)'.
TIME The type shall be `REAL(4)'.
_Return value_:
Elapsed time in seconds since the start of program execution.
_Example_:
program test_etime
integer(8) :: i, j
real, dimension(2) :: tarray
real :: result
call ETIME(tarray, result)
print *, result
print *, tarray(1)
print *, tarray(2)
do i=1,100000000 ! Just a delay
j = i * i - i
end do
call ETIME(tarray, result)
print *, result
print *, tarray(1)
print *, tarray(2)
end program test_etime
_See also_:
*note CPU_TIME::

File: gfortran.info, Node: EVENT_QUERY, Next: EXECUTE_COMMAND_LINE, Prev: ETIME, Up: Intrinsic Procedures
9.99 `EVENT_QUERY' -- Query whether a coarray event has occurred
================================================================
_Description_:
`EVENT_QUERY' assignes the number of events to COUNT which have
been posted to the EVENT variable and not yet been removed by
calling `EVENT WAIT'. When STAT is present and the invocation was
successful, it is assigned the value 0. If it is present and the
invocation has failed, it is assigned a positive value and COUNT
is assigned the value -1.
_Standard_:
TS 18508 or later
_Class_:
subroutine
_Syntax_:
`CALL EVENT_QUERY (EVENT, COUNT [, STAT])'
_Arguments_:
EVENT (intent(IN)) Scalar of type `EVENT_TYPE',
defined in `ISO_FORTRAN_ENV'; shall not be
coindexed.
COUNT (intent(out))Scalar integer with at least the
precision of default integer.
STAT (optional) Scalar default-kind integer
variable.
_Example_:
program atomic
use iso_fortran_env
implicit none
type(event_type) :: event_value_has_been_set[*]
integer :: cnt
if (this_image() == 1) then
call event_query (event_value_has_been_set, cnt)
if (cnt > 0) write(*,*) "Value has been set"
elseif (this_image() == 2) then
event post (event_value_has_been_set[1])
end if
end program atomic

File: gfortran.info, Node: EXECUTE_COMMAND_LINE, Next: EXIT, Prev: EVENT_QUERY, Up: Intrinsic Procedures
9.100 `EXECUTE_COMMAND_LINE' -- Execute a shell command
=======================================================
_Description_:
`EXECUTE_COMMAND_LINE' runs a shell command, synchronously or
asynchronously.
The `COMMAND' argument is passed to the shell and executed (The
shell is `sh' on Unix systems, and `cmd.exe' on Windows.). If
`WAIT' is present and has the value false, the execution of the
command is asynchronous if the system supports it; otherwise, the
command is executed synchronously using the C library's `system'
call.
The three last arguments allow the user to get status information.
After synchronous execution, `EXITSTAT' contains the integer exit
code of the command, as returned by `system'. `CMDSTAT' is set to
zero if the command line was executed (whatever its exit status
was). `CMDMSG' is assigned an error message if an error has
occurred.
Note that the `system' function need not be thread-safe. It is the
responsibility of the user to ensure that `system' is not called
concurrently.
For asynchronous execution on supported targets, the POSIX
`posix_spawn' or `fork' functions are used. Also, a signal
handler for the `SIGCHLD' signal is installed.
_Standard_:
Fortran 2008 and later
_Class_:
Subroutine
_Syntax_:
`CALL EXECUTE_COMMAND_LINE(COMMAND [, WAIT, EXITSTAT, CMDSTAT,
CMDMSG ])'
_Arguments_:
COMMAND Shall be a default `CHARACTER' scalar.
WAIT (Optional) Shall be a default `LOGICAL' scalar.
EXITSTAT (Optional) Shall be an `INTEGER' of the
default kind.
CMDSTAT (Optional) Shall be an `INTEGER' of the
default kind.
CMDMSG (Optional) Shall be an `CHARACTER' scalar of
the default kind.
_Example_:
program test_exec
integer :: i
call execute_command_line ("external_prog.exe", exitstat=i)
print *, "Exit status of external_prog.exe was ", i
call execute_command_line ("reindex_files.exe", wait=.false.)
print *, "Now reindexing files in the background"
end program test_exec
_Note_:
Because this intrinsic is implemented in terms of the `system'
function call, its behavior with respect to signaling is processor
dependent. In particular, on POSIX-compliant systems, the SIGINT
and SIGQUIT signals will be ignored, and the SIGCHLD will be
blocked. As such, if the parent process is terminated, the child
process might not be terminated alongside.
_See also_:
*note SYSTEM::

File: gfortran.info, Node: EXIT, Next: EXP, Prev: EXECUTE_COMMAND_LINE, Up: Intrinsic Procedures
9.101 `EXIT' -- Exit the program with status.
=============================================
_Description_:
`EXIT' causes immediate termination of the program with status.
If status is omitted it returns the canonical _success_ for the
system. All Fortran I/O units are closed.
_Standard_:
GNU extension
_Class_:
Subroutine
_Syntax_:
`CALL EXIT([STATUS])'
_Arguments_:
STATUS Shall be an `INTEGER' of the default kind.
_Return value_:
`STATUS' is passed to the parent process on exit.
_Example_:
program test_exit
integer :: STATUS = 0
print *, 'This program is going to exit.'
call EXIT(STATUS)
end program test_exit
_See also_:
*note ABORT::, *note KILL::

File: gfortran.info, Node: EXP, Next: EXPONENT, Prev: EXIT, Up: Intrinsic Procedures
9.102 `EXP' -- Exponential function
===================================
_Description_:
`EXP(X)' computes the base e exponential of X.
_Standard_:
Fortran 77 and later, has overloads that are GNU extensions
_Class_:
Elemental function
_Syntax_:
`RESULT = EXP(X)'
_Arguments_:
X The type shall be `REAL' or `COMPLEX'.
_Return value_:
The return value has same type and kind as X.
_Example_:
program test_exp
real :: x = 1.0
x = exp(x)
end program test_exp
_Specific names_:
Name Argument Return type Standard
`EXP(X)' `REAL(4) X' `REAL(4)' Fortran 77 and
later
`DEXP(X)' `REAL(8) X' `REAL(8)' Fortran 77 and
later
`CEXP(X)' `COMPLEX(4) `COMPLEX(4)' Fortran 77 and
X' later
`ZEXP(X)' `COMPLEX(8) `COMPLEX(8)' GNU extension
X'
`CDEXP(X)' `COMPLEX(8) `COMPLEX(8)' GNU extension
X'

File: gfortran.info, Node: EXPONENT, Next: EXTENDS_TYPE_OF, Prev: EXP, Up: Intrinsic Procedures
9.103 `EXPONENT' -- Exponent function
=====================================
_Description_:
`EXPONENT(X)' returns the value of the exponent part of X. If X is
zero the value returned is zero.
_Standard_:
Fortran 95 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = EXPONENT(X)'
_Arguments_:
X The type shall be `REAL'.
_Return value_:
The return value is of type default `INTEGER'.
_Example_:
program test_exponent
real :: x = 1.0
integer :: i
i = exponent(x)
print *, i
print *, exponent(0.0)
end program test_exponent

File: gfortran.info, Node: EXTENDS_TYPE_OF, Next: FDATE, Prev: EXPONENT, Up: Intrinsic Procedures
9.104 `EXTENDS_TYPE_OF' -- Query dynamic type for extension
============================================================
_Description_:
Query dynamic type for extension.
_Standard_:
Fortran 2003 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = EXTENDS_TYPE_OF(A, MOLD)'
_Arguments_:
A Shall be an object of extensible declared type
or unlimited polymorphic.
MOLD Shall be an object of extensible declared type
or unlimited polymorphic.
_Return value_:
The return value is a scalar of type default logical. It is true
if and only if the dynamic type of A is an extension type of the
dynamic type of MOLD.
_See also_:
*note SAME_TYPE_AS::

File: gfortran.info, Node: FDATE, Next: FGET, Prev: EXTENDS_TYPE_OF, Up: Intrinsic Procedures
9.105 `FDATE' -- Get the current time as a string
=================================================
_Description_:
`FDATE(DATE)' returns the current date (using the same format as
*note CTIME::) in DATE. It is equivalent to `CALL CTIME(DATE,
TIME())'.
This intrinsic is provided in both subroutine and function forms;
however, only one form can be used in any given program unit.
_Standard_:
GNU extension
_Class_:
Subroutine, function
_Syntax_:
`CALL FDATE(DATE)'.
`DATE = FDATE()'.
_Arguments_:
DATE The type shall be of type `CHARACTER' of the
default kind. It is an `INTENT(OUT)' argument.
If the length of this variable is too short
for the date and time string to fit
completely, it will be blank on procedure
return.
_Return value_:
The current date and time as a string.
_Example_:
program test_fdate
integer(8) :: i, j
character(len=30) :: date
call fdate(date)
print *, 'Program started on ', date
do i = 1, 100000000 ! Just a delay
j = i * i - i
end do
call fdate(date)
print *, 'Program ended on ', date
end program test_fdate
_See also_:
*note DATE_AND_TIME::, *note CTIME::

File: gfortran.info, Node: FGET, Next: FGETC, Prev: FDATE, Up: Intrinsic Procedures
9.106 `FGET' -- Read a single character in stream mode from stdin
=================================================================
_Description_:
Read a single character in stream mode from stdin by bypassing
normal formatted output. Stream I/O should not be mixed with
normal record-oriented (formatted or unformatted) I/O on the same
unit; the results are unpredictable.
This intrinsic is provided in both subroutine and function forms;
however, only one form can be used in any given program unit.
Note that the `FGET' intrinsic is provided for backwards
compatibility with `g77'. GNU Fortran provides the Fortran 2003
Stream facility. Programmers should consider the use of new
stream IO feature in new code for future portability. See also
*note Fortran 2003 status::.
_Standard_:
GNU extension
_Class_:
Subroutine, function
_Syntax_:
`CALL FGET(C [, STATUS])'
`STATUS = FGET(C)'
_Arguments_:
C The type shall be `CHARACTER' and of default
kind.
STATUS (Optional) status flag of type `INTEGER'.
Returns 0 on success, -1 on end-of-file, and a
system specific positive error code otherwise.
_Example_:
PROGRAM test_fget
INTEGER, PARAMETER :: strlen = 100
INTEGER :: status, i = 1
CHARACTER(len=strlen) :: str = ""
WRITE (*,*) 'Enter text:'
DO
CALL fget(str(i:i), status)
if (status /= 0 .OR. i > strlen) exit
i = i + 1
END DO
WRITE (*,*) TRIM(str)
END PROGRAM
_See also_:
*note FGETC::, *note FPUT::, *note FPUTC::

File: gfortran.info, Node: FGETC, Next: FINDLOC, Prev: FGET, Up: Intrinsic Procedures
9.107 `FGETC' -- Read a single character in stream mode
=======================================================
_Description_:
Read a single character in stream mode by bypassing normal
formatted output. Stream I/O should not be mixed with normal
record-oriented (formatted or unformatted) I/O on the same unit;
the results are unpredictable.
This intrinsic is provided in both subroutine and function forms;
however, only one form can be used in any given program unit.
Note that the `FGET' intrinsic is provided for backwards
compatibility with `g77'. GNU Fortran provides the Fortran 2003
Stream facility. Programmers should consider the use of new
stream IO feature in new code for future portability. See also
*note Fortran 2003 status::.
_Standard_:
GNU extension
_Class_:
Subroutine, function
_Syntax_:
`CALL FGETC(UNIT, C [, STATUS])'
`STATUS = FGETC(UNIT, C)'
_Arguments_:
UNIT The type shall be `INTEGER'.
C The type shall be `CHARACTER' and of default
kind.
STATUS (Optional) status flag of type `INTEGER'.
Returns 0 on success, -1 on end-of-file and a
system specific positive error code otherwise.
_Example_:
PROGRAM test_fgetc
INTEGER :: fd = 42, status
CHARACTER :: c
OPEN(UNIT=fd, FILE="/etc/passwd", ACTION="READ", STATUS = "OLD")
DO
CALL fgetc(fd, c, status)
IF (status /= 0) EXIT
call fput(c)
END DO
CLOSE(UNIT=fd)
END PROGRAM
_See also_:
*note FGET::, *note FPUT::, *note FPUTC::

File: gfortran.info, Node: FINDLOC, Next: FLOOR, Prev: FGETC, Up: Intrinsic Procedures
9.108 `FINDLOC' -- Search an array for a value
==============================================
_Description_:
Determines the location of the element in the array with the value
given in the VALUE argument, or, if the DIM argument is supplied,
determines the locations of the maximum element along each row of
the array in the DIM direction. If MASK is present, only the
elements for which MASK is `.TRUE.' are considered. If more than
one element in the array has the value VALUE, the location
returned is that of the first such element in array element order
if the BACK is not present or if it is `.FALSE.'. If BACK is true,
the location returned is that of the last such element. If the
array has zero size, or all of the elements of MASK are `.FALSE.',
then the result is an array of zeroes. Similarly, if DIM is
supplied and all of the elements of MASK along a given row are
zero, the result value for that row is zero.
_Standard_:
Fortran 2008 and later.
_Class_:
Transformational function
_Syntax_:
`RESULT = FINDLOC(ARRAY, VALUE, DIM [, MASK] [,KIND]
[,BACK])'
`RESULT = FINDLOC(ARRAY, VALUE, [, MASK] [,KIND]
[,BACK])'
_Arguments_:
ARRAY Shall be an array of intrinsic type.
VALUE A scalar of intrinsic type which is in type
conformance with ARRAY.
DIM (Optional) Shall be a scalar of type
`INTEGER', with a value between one and the
rank of ARRAY, inclusive. It may not be an
optional dummy argument.
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
BACK (Optional) A scalar of type `LOGICAL'.
_Return value_:
If DIM is absent, the result is a rank-one array with a length
equal to the rank of ARRAY. If DIM is present, the result is an
array with a rank one less than the rank of ARRAY, and a size
corresponding to the size of ARRAY with the DIM dimension removed.
If DIM is present and ARRAY has a rank of one, the result is a
scalar. If the optional argument KIND is present, the result is
an integer of kind KIND, otherwise it is of default kind.
_See also_:
*note MAXLOC::, *note MINLOC::

File: gfortran.info, Node: FLOOR, Next: FLUSH, Prev: FINDLOC, Up: Intrinsic Procedures
9.109 `FLOOR' -- Integer floor function
=======================================
_Description_:
`FLOOR(A)' returns the greatest integer less than or equal to X.
_Standard_:
Fortran 95 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = FLOOR(A [, KIND])'
_Arguments_:
A The type shall be `REAL'.
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
_Return value_:
The return value is of type `INTEGER(KIND)' if KIND is present and
of default-kind `INTEGER' otherwise.
_Example_:
program test_floor
real :: x = 63.29
real :: y = -63.59
print *, floor(x) ! returns 63
print *, floor(y) ! returns -64
end program test_floor
_See also_:
*note CEILING::, *note NINT::

File: gfortran.info, Node: FLUSH, Next: FNUM, Prev: FLOOR, Up: Intrinsic Procedures
9.110 `FLUSH' -- Flush I/O unit(s)
==================================
_Description_:
Flushes Fortran unit(s) currently open for output. Without the
optional argument, all units are flushed, otherwise just the unit
specified.
_Standard_:
GNU extension
_Class_:
Subroutine
_Syntax_:
`CALL FLUSH(UNIT)'
_Arguments_:
UNIT (Optional) The type shall be `INTEGER'.
_Note_:
Beginning with the Fortran 2003 standard, there is a `FLUSH'
statement that should be preferred over the `FLUSH' intrinsic.
The `FLUSH' intrinsic and the Fortran 2003 `FLUSH' statement have
identical effect: they flush the runtime library's I/O buffer so
that the data becomes visible to other processes. This does not
guarantee that the data is committed to disk.
On POSIX systems, you can request that all data is transferred to
the storage device by calling the `fsync' function, with the POSIX
file descriptor of the I/O unit as argument (retrieved with GNU
intrinsic `FNUM'). The following example shows how:
! Declare the interface for POSIX fsync function
interface
function fsync (fd) bind(c,name="fsync")
use iso_c_binding, only: c_int
integer(c_int), value :: fd
integer(c_int) :: fsync
end function fsync
end interface
! Variable declaration
integer :: ret
! Opening unit 10
open (10,file="foo")
! ...
! Perform I/O on unit 10
! ...
! Flush and sync
flush(10)
ret = fsync(fnum(10))
! Handle possible error
if (ret /= 0) stop "Error calling FSYNC"

File: gfortran.info, Node: FNUM, Next: FPUT, Prev: FLUSH, Up: Intrinsic Procedures
9.111 `FNUM' -- File number function
====================================
_Description_:
`FNUM(UNIT)' returns the POSIX file descriptor number
corresponding to the open Fortran I/O unit `UNIT'.
_Standard_:
GNU extension
_Class_:
Function
_Syntax_:
`RESULT = FNUM(UNIT)'
_Arguments_:
UNIT The type shall be `INTEGER'.
_Return value_:
The return value is of type `INTEGER'
_Example_:
program test_fnum
integer :: i
open (unit=10, status = "scratch")
i = fnum(10)
print *, i
close (10)
end program test_fnum

File: gfortran.info, Node: FPUT, Next: FPUTC, Prev: FNUM, Up: Intrinsic Procedures
9.112 `FPUT' -- Write a single character in stream mode to stdout
=================================================================
_Description_:
Write a single character in stream mode to stdout by bypassing
normal formatted output. Stream I/O should not be mixed with
normal record-oriented (formatted or unformatted) I/O on the same
unit; the results are unpredictable.
This intrinsic is provided in both subroutine and function forms;
however, only one form can be used in any given program unit.
Note that the `FGET' intrinsic is provided for backwards
compatibility with `g77'. GNU Fortran provides the Fortran 2003
Stream facility. Programmers should consider the use of new
stream IO feature in new code for future portability. See also
*note Fortran 2003 status::.
_Standard_:
GNU extension
_Class_:
Subroutine, function
_Syntax_:
`CALL FPUT(C [, STATUS])'
`STATUS = FPUT(C)'
_Arguments_:
C The type shall be `CHARACTER' and of default
kind.
STATUS (Optional) status flag of type `INTEGER'.
Returns 0 on success, -1 on end-of-file and a
system specific positive error code otherwise.
_Example_:
PROGRAM test_fput
CHARACTER(len=10) :: str = "gfortran"
INTEGER :: i
DO i = 1, len_trim(str)
CALL fput(str(i:i))
END DO
END PROGRAM
_See also_:
*note FPUTC::, *note FGET::, *note FGETC::

File: gfortran.info, Node: FPUTC, Next: FRACTION, Prev: FPUT, Up: Intrinsic Procedures
9.113 `FPUTC' -- Write a single character in stream mode
========================================================
_Description_:
Write a single character in stream mode by bypassing normal
formatted output. Stream I/O should not be mixed with normal
record-oriented (formatted or unformatted) I/O on the same unit;
the results are unpredictable.
This intrinsic is provided in both subroutine and function forms;
however, only one form can be used in any given program unit.
Note that the `FGET' intrinsic is provided for backwards
compatibility with `g77'. GNU Fortran provides the Fortran 2003
Stream facility. Programmers should consider the use of new
stream IO feature in new code for future portability. See also
*note Fortran 2003 status::.
_Standard_:
GNU extension
_Class_:
Subroutine, function
_Syntax_:
`CALL FPUTC(UNIT, C [, STATUS])'
`STATUS = FPUTC(UNIT, C)'
_Arguments_:
UNIT The type shall be `INTEGER'.
C The type shall be `CHARACTER' and of default
kind.
STATUS (Optional) status flag of type `INTEGER'.
Returns 0 on success, -1 on end-of-file and a
system specific positive error code otherwise.
_Example_:
PROGRAM test_fputc
CHARACTER(len=10) :: str = "gfortran"
INTEGER :: fd = 42, i
OPEN(UNIT = fd, FILE = "out", ACTION = "WRITE", STATUS="NEW")
DO i = 1, len_trim(str)
CALL fputc(fd, str(i:i))
END DO
CLOSE(fd)
END PROGRAM
_See also_:
*note FPUT::, *note FGET::, *note FGETC::

File: gfortran.info, Node: FRACTION, Next: FREE, Prev: FPUTC, Up: Intrinsic Procedures
9.114 `FRACTION' -- Fractional part of the model representation
===============================================================
_Description_:
`FRACTION(X)' returns the fractional part of the model
representation of `X'.
_Standard_:
Fortran 95 and later
_Class_:
Elemental function
_Syntax_:
`Y = FRACTION(X)'
_Arguments_:
X The type of the argument shall be a `REAL'.
_Return value_:
The return value is of the same type and kind as the argument.
The fractional part of the model representation of `X' is returned;
it is `X * RADIX(X)**(-EXPONENT(X))'.
_Example_:
program test_fraction
real :: x
x = 178.1387e-4
print *, fraction(x), x * radix(x)**(-exponent(x))
end program test_fraction

File: gfortran.info, Node: FREE, Next: FSEEK, Prev: FRACTION, Up: Intrinsic Procedures
9.115 `FREE' -- Frees memory
============================
_Description_:
Frees memory previously allocated by `MALLOC'. The `FREE'
intrinsic is an extension intended to be used with Cray pointers,
and is provided in GNU Fortran to allow user to compile legacy
code. For new code using Fortran 95 pointers, the memory
de-allocation intrinsic is `DEALLOCATE'.
_Standard_:
GNU extension
_Class_:
Subroutine
_Syntax_:
`CALL FREE(PTR)'
_Arguments_:
PTR The type shall be `INTEGER'. It represents the
location of the memory that should be
de-allocated.
_Return value_:
None
_Example_:
See `MALLOC' for an example.
_See also_:
*note MALLOC::

File: gfortran.info, Node: FSEEK, Next: FSTAT, Prev: FREE, Up: Intrinsic Procedures
9.116 `FSEEK' -- Low level file positioning subroutine
======================================================
_Description_:
Moves UNIT to the specified OFFSET. If WHENCE is set to 0, the
OFFSET is taken as an absolute value `SEEK_SET', if set to 1,
OFFSET is taken to be relative to the current position `SEEK_CUR',
and if set to 2 relative to the end of the file `SEEK_END'. On
error, STATUS is set to a nonzero value. If STATUS the seek fails
silently.
This intrinsic routine is not fully backwards compatible with
`g77'. In `g77', the `FSEEK' takes a statement label instead of a
STATUS variable. If FSEEK is used in old code, change
CALL FSEEK(UNIT, OFFSET, WHENCE, *label)
to
INTEGER :: status
CALL FSEEK(UNIT, OFFSET, WHENCE, status)
IF (status /= 0) GOTO label
Please note that GNU Fortran provides the Fortran 2003 Stream
facility. Programmers should consider the use of new stream IO
feature in new code for future portability. See also *note Fortran
2003 status::.
_Standard_:
GNU extension
_Class_:
Subroutine
_Syntax_:
`CALL FSEEK(UNIT, OFFSET, WHENCE[, STATUS])'
_Arguments_:
UNIT Shall be a scalar of type `INTEGER'.
OFFSET Shall be a scalar of type `INTEGER'.
WHENCE Shall be a scalar of type `INTEGER'. Its
value shall be either 0, 1 or 2.
STATUS (Optional) shall be a scalar of type
`INTEGER(4)'.
_Example_:
PROGRAM test_fseek
INTEGER, PARAMETER :: SEEK_SET = 0, SEEK_CUR = 1, SEEK_END = 2
INTEGER :: fd, offset, ierr
ierr = 0
offset = 5
fd = 10
OPEN(UNIT=fd, FILE="fseek.test")
CALL FSEEK(fd, offset, SEEK_SET, ierr) ! move to OFFSET
print *, FTELL(fd), ierr
CALL FSEEK(fd, 0, SEEK_END, ierr) ! move to end
print *, FTELL(fd), ierr
CALL FSEEK(fd, 0, SEEK_SET, ierr) ! move to beginning
print *, FTELL(fd), ierr
CLOSE(UNIT=fd)
END PROGRAM
_See also_:
*note FTELL::

File: gfortran.info, Node: FSTAT, Next: FTELL, Prev: FSEEK, Up: Intrinsic Procedures
9.117 `FSTAT' -- Get file status
================================
_Description_:
`FSTAT' is identical to *note STAT::, except that information
about an already opened file is obtained.
The elements in `VALUES' are the same as described by *note STAT::.
This intrinsic is provided in both subroutine and function forms;
however, only one form can be used in any given program unit.
_Standard_:
GNU extension
_Class_:
Subroutine, function
_Syntax_:
`CALL FSTAT(UNIT, VALUES [, STATUS])'
`STATUS = FSTAT(UNIT, VALUES)'
_Arguments_:
UNIT An open I/O unit number of type `INTEGER'.
VALUES The type shall be `INTEGER(4), DIMENSION(13)'.
STATUS (Optional) status flag of type `INTEGER(4)'.
Returns 0 on success and a system specific
error code otherwise.
_Example_:
See *note STAT:: for an example.
_See also_:
To stat a link: *note LSTAT::, to stat a file: *note STAT::

File: gfortran.info, Node: FTELL, Next: GAMMA, Prev: FSTAT, Up: Intrinsic Procedures
9.118 `FTELL' -- Current stream position
========================================
_Description_:
Retrieves the current position within an open file.
This intrinsic is provided in both subroutine and function forms;
however, only one form can be used in any given program unit.
_Standard_:
GNU extension
_Class_:
Subroutine, function
_Syntax_:
`CALL FTELL(UNIT, OFFSET)'
`OFFSET = FTELL(UNIT)'
_Arguments_:
OFFSET Shall of type `INTEGER'.
UNIT Shall of type `INTEGER'.
_Return value_:
In either syntax, OFFSET is set to the current offset of unit
number UNIT, or to -1 if the unit is not currently open.
_Example_:
PROGRAM test_ftell
INTEGER :: i
OPEN(10, FILE="temp.dat")
CALL ftell(10,i)
WRITE(*,*) i
END PROGRAM
_See also_:
*note FSEEK::

File: gfortran.info, Node: GAMMA, Next: GERROR, Prev: FTELL, Up: Intrinsic Procedures
9.119 `GAMMA' -- Gamma function
===============================
_Description_:
`GAMMA(X)' computes Gamma (\Gamma) of X. For positive, integer
values of X the Gamma function simplifies to the factorial
function \Gamma(x)=(x-1)!.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`X = GAMMA(X)'
_Arguments_:
X Shall be of type `REAL' and neither zero nor a
negative integer.
_Return value_:
The return value is of type `REAL' of the same kind as X.
_Example_:
program test_gamma
real :: x = 1.0
x = gamma(x) ! returns 1.0
end program test_gamma
_Specific names_:
Name Argument Return type Standard
`GAMMA(X)' `REAL(4) X' `REAL(4)' GNU Extension
`DGAMMA(X)' `REAL(8) X' `REAL(8)' GNU Extension
_See also_:
Logarithm of the Gamma function: *note LOG_GAMMA::

File: gfortran.info, Node: GERROR, Next: GETARG, Prev: GAMMA, Up: Intrinsic Procedures
9.120 `GERROR' -- Get last system error message
===============================================
_Description_:
Returns the system error message corresponding to the last system
error. This resembles the functionality of `strerror(3)' in C.
_Standard_:
GNU extension
_Class_:
Subroutine
_Syntax_:
`CALL GERROR(RESULT)'
_Arguments_:
RESULT Shall of type `CHARACTER' and of default
_Example_:
PROGRAM test_gerror
CHARACTER(len=100) :: msg
CALL gerror(msg)
WRITE(*,*) msg
END PROGRAM
_See also_:
*note IERRNO::, *note PERROR::

File: gfortran.info, Node: GETARG, Next: GET_COMMAND, Prev: GERROR, Up: Intrinsic Procedures
9.121 `GETARG' -- Get command line arguments
============================================
_Description_:
Retrieve the POS-th argument that was passed on the command line
when the containing program was invoked.
This intrinsic routine is provided for backwards compatibility with
GNU Fortran 77. In new code, programmers should consider the use
of the *note GET_COMMAND_ARGUMENT:: intrinsic defined by the
Fortran 2003 standard.
_Standard_:
GNU extension
_Class_:
Subroutine
_Syntax_:
`CALL GETARG(POS, VALUE)'
_Arguments_:
POS Shall be of type `INTEGER' and not wider than
the default integer kind; POS \geq 0
VALUE Shall be of type `CHARACTER' and of default
kind.
VALUE Shall be of type `CHARACTER'.
_Return value_:
After `GETARG' returns, the VALUE argument holds the POSth command
line argument. If VALUE cannot hold the argument, it is truncated
to fit the length of VALUE. If there are less than POS arguments
specified at the command line, VALUE will be filled with blanks.
If POS = 0, VALUE is set to the name of the program (on systems
that support this feature).
_Example_:
PROGRAM test_getarg
INTEGER :: i
CHARACTER(len=32) :: arg
DO i = 1, iargc()
CALL getarg(i, arg)
WRITE (*,*) arg
END DO
END PROGRAM
_See also_:
GNU Fortran 77 compatibility function: *note IARGC::
Fortran 2003 functions and subroutines: *note GET_COMMAND::, *note
GET_COMMAND_ARGUMENT::, *note COMMAND_ARGUMENT_COUNT::

File: gfortran.info, Node: GET_COMMAND, Next: GET_COMMAND_ARGUMENT, Prev: GETARG, Up: Intrinsic Procedures
9.122 `GET_COMMAND' -- Get the entire command line
==================================================
_Description_:
Retrieve the entire command line that was used to invoke the
program.
_Standard_:
Fortran 2003 and later
_Class_:
Subroutine
_Syntax_:
`CALL GET_COMMAND([COMMAND, LENGTH, STATUS])'
_Arguments_:
COMMAND (Optional) shall be of type `CHARACTER' and of
default kind.
LENGTH (Optional) Shall be of type `INTEGER' and of
default kind.
STATUS (Optional) Shall be of type `INTEGER' and of
default kind.
_Return value_:
If COMMAND is present, stores the entire command line that was used
to invoke the program in COMMAND. If LENGTH is present, it is
assigned the length of the command line. If STATUS is present, it
is assigned 0 upon success of the command, -1 if COMMAND is too
short to store the command line, or a positive value in case of an
error.
_Example_:
PROGRAM test_get_command
CHARACTER(len=255) :: cmd
CALL get_command(cmd)
WRITE (*,*) TRIM(cmd)
END PROGRAM
_See also_:
*note GET_COMMAND_ARGUMENT::, *note COMMAND_ARGUMENT_COUNT::

File: gfortran.info, Node: GET_COMMAND_ARGUMENT, Next: GETCWD, Prev: GET_COMMAND, Up: Intrinsic Procedures
9.123 `GET_COMMAND_ARGUMENT' -- Get command line arguments
==========================================================
_Description_:
Retrieve the NUMBER-th argument that was passed on the command
line when the containing program was invoked.
_Standard_:
Fortran 2003 and later
_Class_:
Subroutine
_Syntax_:
`CALL GET_COMMAND_ARGUMENT(NUMBER [, VALUE, LENGTH, STATUS])'
_Arguments_:
NUMBER Shall be a scalar of type `INTEGER' and of
default kind, NUMBER \geq 0
VALUE (Optional) Shall be a scalar of type
`CHARACTER' and of default kind.
LENGTH (Optional) Shall be a scalar of type `INTEGER'
and of default kind.
STATUS (Optional) Shall be a scalar of type `INTEGER'
and of default kind.
_Return value_:
After `GET_COMMAND_ARGUMENT' returns, the VALUE argument holds the
NUMBER-th command line argument. If VALUE cannot hold the
argument, it is truncated to fit the length of VALUE. If there are
less than NUMBER arguments specified at the command line, VALUE
will be filled with blanks. If NUMBER = 0, VALUE is set to the
name of the program (on systems that support this feature). The
LENGTH argument contains the length of the NUMBER-th command line
argument. If the argument retrieval fails, STATUS is a positive
number; if VALUE contains a truncated command line argument,
STATUS is -1; and otherwise the STATUS is zero.
_Example_:
PROGRAM test_get_command_argument
INTEGER :: i
CHARACTER(len=32) :: arg
i = 0
DO
CALL get_command_argument(i, arg)
IF (LEN_TRIM(arg) == 0) EXIT
WRITE (*,*) TRIM(arg)
i = i+1
END DO
END PROGRAM
_See also_:
*note GET_COMMAND::, *note COMMAND_ARGUMENT_COUNT::

File: gfortran.info, Node: GETCWD, Next: GETENV, Prev: GET_COMMAND_ARGUMENT, Up: Intrinsic Procedures
9.124 `GETCWD' -- Get current working directory
===============================================
_Description_:
Get current working directory.
This intrinsic is provided in both subroutine and function forms;
however, only one form can be used in any given program unit.
_Standard_:
GNU extension
_Class_:
Subroutine, function
_Syntax_:
`CALL GETCWD(C [, STATUS])'
`STATUS = GETCWD(C)'
_Arguments_:
C The type shall be `CHARACTER' and of default
kind.
STATUS (Optional) status flag. Returns 0 on success,
a system specific and nonzero error code
otherwise.
_Example_:
PROGRAM test_getcwd
CHARACTER(len=255) :: cwd
CALL getcwd(cwd)
WRITE(*,*) TRIM(cwd)
END PROGRAM
_See also_:
*note CHDIR::

File: gfortran.info, Node: GETENV, Next: GET_ENVIRONMENT_VARIABLE, Prev: GETCWD, Up: Intrinsic Procedures
9.125 `GETENV' -- Get an environmental variable
===============================================
_Description_:
Get the VALUE of the environmental variable NAME.
This intrinsic routine is provided for backwards compatibility with
GNU Fortran 77. In new code, programmers should consider the use
of the *note GET_ENVIRONMENT_VARIABLE:: intrinsic defined by the
Fortran 2003 standard.
Note that `GETENV' need not be thread-safe. It is the
responsibility of the user to ensure that the environment is not
being updated concurrently with a call to the `GETENV' intrinsic.
_Standard_:
GNU extension
_Class_:
Subroutine
_Syntax_:
`CALL GETENV(NAME, VALUE)'
_Arguments_:
NAME Shall be of type `CHARACTER' and of default
kind.
VALUE Shall be of type `CHARACTER' and of default
kind.
_Return value_:
Stores the value of NAME in VALUE. If VALUE is not large enough to
hold the data, it is truncated. If NAME is not set, VALUE will be
filled with blanks.
_Example_:
PROGRAM test_getenv
CHARACTER(len=255) :: homedir
CALL getenv("HOME", homedir)
WRITE (*,*) TRIM(homedir)
END PROGRAM
_See also_:
*note GET_ENVIRONMENT_VARIABLE::

File: gfortran.info, Node: GET_ENVIRONMENT_VARIABLE, Next: GETGID, Prev: GETENV, Up: Intrinsic Procedures
9.126 `GET_ENVIRONMENT_VARIABLE' -- Get an environmental variable
=================================================================
_Description_:
Get the VALUE of the environmental variable NAME.
Note that `GET_ENVIRONMENT_VARIABLE' need not be thread-safe. It
is the responsibility of the user to ensure that the environment is
not being updated concurrently with a call to the
`GET_ENVIRONMENT_VARIABLE' intrinsic.
_Standard_:
Fortran 2003 and later
_Class_:
Subroutine
_Syntax_:
`CALL GET_ENVIRONMENT_VARIABLE(NAME[, VALUE, LENGTH, STATUS,
TRIM_NAME)'
_Arguments_:
NAME Shall be a scalar of type `CHARACTER' and of
default kind.
VALUE (Optional) Shall be a scalar of type
`CHARACTER' and of default kind.
LENGTH (Optional) Shall be a scalar of type `INTEGER'
and of default kind.
STATUS (Optional) Shall be a scalar of type `INTEGER'
and of default kind.
TRIM_NAME (Optional) Shall be a scalar of type `LOGICAL'
and of default kind.
_Return value_:
Stores the value of NAME in VALUE. If VALUE is not large enough to
hold the data, it is truncated. If NAME is not set, VALUE will be
filled with blanks. Argument LENGTH contains the length needed for
storing the environment variable NAME or zero if it is not
present. STATUS is -1 if VALUE is present but too short for the
environment variable; it is 1 if the environment variable does not
exist and 2 if the processor does not support environment
variables; in all other cases STATUS is zero. If TRIM_NAME is
present with the value `.FALSE.', the trailing blanks in NAME are
significant; otherwise they are not part of the environment
variable name.
_Example_:
PROGRAM test_getenv
CHARACTER(len=255) :: homedir
CALL get_environment_variable("HOME", homedir)
WRITE (*,*) TRIM(homedir)
END PROGRAM

File: gfortran.info, Node: GETGID, Next: GETLOG, Prev: GET_ENVIRONMENT_VARIABLE, Up: Intrinsic Procedures
9.127 `GETGID' -- Group ID function
===================================
_Description_:
Returns the numerical group ID of the current process.
_Standard_:
GNU extension
_Class_:
Function
_Syntax_:
`RESULT = GETGID()'
_Return value_:
The return value of `GETGID' is an `INTEGER' of the default kind.
_Example_:
See `GETPID' for an example.
_See also_:
*note GETPID::, *note GETUID::

File: gfortran.info, Node: GETLOG, Next: GETPID, Prev: GETGID, Up: Intrinsic Procedures
9.128 `GETLOG' -- Get login name
================================
_Description_:
Gets the username under which the program is running.
_Standard_:
GNU extension
_Class_:
Subroutine
_Syntax_:
`CALL GETLOG(C)'
_Arguments_:
C Shall be of type `CHARACTER' and of default
kind.
_Return value_:
Stores the current user name in LOGIN. (On systems where POSIX
functions `geteuid' and `getpwuid' are not available, and the
`getlogin' function is not implemented either, this will return a
blank string.)
_Example_:
PROGRAM TEST_GETLOG
CHARACTER(32) :: login
CALL GETLOG(login)
WRITE(*,*) login
END PROGRAM
_See also_:
*note GETUID::

File: gfortran.info, Node: GETPID, Next: GETUID, Prev: GETLOG, Up: Intrinsic Procedures
9.129 `GETPID' -- Process ID function
=====================================
_Description_:
Returns the numerical process identifier of the current process.
_Standard_:
GNU extension
_Class_:
Function
_Syntax_:
`RESULT = GETPID()'
_Return value_:
The return value of `GETPID' is an `INTEGER' of the default kind.
_Example_:
program info
print *, "The current process ID is ", getpid()
print *, "Your numerical user ID is ", getuid()
print *, "Your numerical group ID is ", getgid()
end program info
_See also_:
*note GETGID::, *note GETUID::

File: gfortran.info, Node: GETUID, Next: GMTIME, Prev: GETPID, Up: Intrinsic Procedures
9.130 `GETUID' -- User ID function
==================================
_Description_:
Returns the numerical user ID of the current process.
_Standard_:
GNU extension
_Class_:
Function
_Syntax_:
`RESULT = GETUID()'
_Return value_:
The return value of `GETUID' is an `INTEGER' of the default kind.
_Example_:
See `GETPID' for an example.
_See also_:
*note GETPID::, *note GETLOG::

File: gfortran.info, Node: GMTIME, Next: HOSTNM, Prev: GETUID, Up: Intrinsic Procedures
9.131 `GMTIME' -- Convert time to GMT info
==========================================
_Description_:
Given a system time value TIME (as provided by the *note TIME::
intrinsic), fills VALUES with values extracted from it appropriate
to the UTC time zone (Universal Coordinated Time, also known in
some countries as GMT, Greenwich Mean Time), using `gmtime(3)'.
This intrinsic routine is provided for backwards compatibility with
GNU Fortran 77. In new code, programmers should consider the use
of the *note DATE_AND_TIME:: intrinsic defined by the Fortran 95
standard.
_Standard_:
GNU extension
_Class_:
Subroutine
_Syntax_:
`CALL GMTIME(TIME, VALUES)'
_Arguments_:
TIME An `INTEGER' scalar expression corresponding
to a system time, with `INTENT(IN)'.
VALUES A default `INTEGER' array with 9 elements,
with `INTENT(OUT)'.
_Return value_:
The elements of VALUES are assigned as follows:
1. Seconds after the minute, range 0-59 or 0-61 to allow for leap
seconds
2. Minutes after the hour, range 0-59
3. Hours past midnight, range 0-23
4. Day of month, range 1-31
5. Number of months since January, range 0-11
6. Years since 1900
7. Number of days since Sunday, range 0-6
8. Days since January 1, range 0-365
9. Daylight savings indicator: positive if daylight savings is in
effect, zero if not, and negative if the information is not
available.
_See also_:
*note DATE_AND_TIME::, *note CTIME::, *note LTIME::, *note TIME::,
*note TIME8::

File: gfortran.info, Node: HOSTNM, Next: HUGE, Prev: GMTIME, Up: Intrinsic Procedures
9.132 `HOSTNM' -- Get system host name
======================================
_Description_:
Retrieves the host name of the system on which the program is
running.
This intrinsic is provided in both subroutine and function forms;
however, only one form can be used in any given program unit.
_Standard_:
GNU extension
_Class_:
Subroutine, function
_Syntax_:
`CALL HOSTNM(C [, STATUS])'
`STATUS = HOSTNM(NAME)'
_Arguments_:
C Shall of type `CHARACTER' and of default kind.
STATUS (Optional) status flag of type `INTEGER'.
Returns 0 on success, or a system specific
error code otherwise.
_Return value_:
In either syntax, NAME is set to the current hostname if it can be
obtained, or to a blank string otherwise.

File: gfortran.info, Node: HUGE, Next: HYPOT, Prev: HOSTNM, Up: Intrinsic Procedures
9.133 `HUGE' -- Largest number of a kind
========================================
_Description_:
`HUGE(X)' returns the largest number that is not an infinity in
the model of the type of `X'.
_Standard_:
Fortran 95 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = HUGE(X)'
_Arguments_:
X Shall be of type `REAL' or `INTEGER'.
_Return value_:
The return value is of the same type and kind as X
_Example_:
program test_huge_tiny
print *, huge(0), huge(0.0), huge(0.0d0)
print *, tiny(0.0), tiny(0.0d0)
end program test_huge_tiny

File: gfortran.info, Node: HYPOT, Next: IACHAR, Prev: HUGE, Up: Intrinsic Procedures
9.134 `HYPOT' -- Euclidean distance function
============================================
_Description_:
`HYPOT(X,Y)' is the Euclidean distance function. It is equal to
\sqrtX^2 + Y^2, without undue underflow or overflow.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = HYPOT(X, Y)'
_Arguments_:
X The type shall be `REAL'.
Y The type and kind type parameter shall be the
same as X.
_Return value_:
The return value has the same type and kind type parameter as X.
_Example_:
program test_hypot
real(4) :: x = 1.e0_4, y = 0.5e0_4
x = hypot(x,y)
end program test_hypot

File: gfortran.info, Node: IACHAR, Next: IALL, Prev: HYPOT, Up: Intrinsic Procedures
9.135 `IACHAR' -- Code in ASCII collating sequence
==================================================
_Description_:
`IACHAR(C)' returns the code for the ASCII character in the first
character position of `C'.
_Standard_:
Fortran 95 and later, with KIND argument Fortran 2003 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = IACHAR(C [, KIND])'
_Arguments_:
C Shall be a scalar `CHARACTER', with
`INTENT(IN)'
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
_Return value_:
The return value is of type `INTEGER' and of kind KIND. If KIND is
absent, the return value is of default integer kind.
_Example_:
program test_iachar
integer i
i = iachar(' ')
end program test_iachar
_Note_:
See *note ICHAR:: for a discussion of converting between numerical
values and formatted string representations.
_See also_:
*note ACHAR::, *note CHAR::, *note ICHAR::

File: gfortran.info, Node: IALL, Next: IAND, Prev: IACHAR, Up: Intrinsic Procedures
9.136 `IALL' -- Bitwise AND of array elements
=============================================
_Description_:
Reduces with bitwise AND the elements of ARRAY along dimension DIM
if the corresponding element in MASK is `TRUE'.
_Standard_:
Fortran 2008 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = IALL(ARRAY[, MASK])'
`RESULT = IALL(ARRAY, DIM[, MASK])'
_Arguments_:
ARRAY Shall be an array of type `INTEGER'
DIM (Optional) shall be a scalar of type `INTEGER'
with a value in the range from 1 to n, where n
equals the rank of ARRAY.
MASK (Optional) shall be of type `LOGICAL' and
either be a scalar or an array of the same
shape as ARRAY.
_Return value_:
The result is of the same type as ARRAY.
If DIM is absent, a scalar with the bitwise ALL of all elements in
ARRAY is returned. Otherwise, an array of rank n-1, where n equals
the rank of ARRAY, and a shape similar to that of ARRAY with
dimension DIM dropped is returned.
_Example_:
PROGRAM test_iall
INTEGER(1) :: a(2)
a(1) = b'00100100'
a(2) = b'01101010'
! prints 00100000
PRINT '(b8.8)', IALL(a)
END PROGRAM
_See also_:
*note IANY::, *note IPARITY::, *note IAND::

File: gfortran.info, Node: IAND, Next: IANY, Prev: IALL, Up: Intrinsic Procedures
9.137 `IAND' -- Bitwise logical and
===================================
_Description_:
Bitwise logical `AND'.
_Standard_:
Fortran 95 and later, has overloads that are GNU extensions
_Class_:
Elemental function
_Syntax_:
`RESULT = IAND(I, J)'
_Arguments_:
I The type shall be `INTEGER' or a
boz-literal-constant.
J The type shall be `INTEGER' with the same kind
type parameter as I or a boz-literal-constant.
I and J shall not both be
boz-literal-constants.
_Return value_:
The return type is `INTEGER' with the kind type parameter of the
arguments. A boz-literal-constant is converted to an `INTEGER'
with the kind type parameter of the other argument as-if a call to
*note INT:: occurred.
_Example_:
PROGRAM test_iand
INTEGER :: a, b
DATA a / Z'F' /, b / Z'3' /
WRITE (*,*) IAND(a, b)
END PROGRAM
_Specific names_:
Name Argument Return type Standard
`IAND(A)' `INTEGER A' `INTEGER' Fortran 95 and
later
`BIAND(A)' `INTEGER(1) `INTEGER(1)' GNU extension
A'
`IIAND(A)' `INTEGER(2) `INTEGER(2)' GNU extension
A'
`JIAND(A)' `INTEGER(4) `INTEGER(4)' GNU extension
A'
`KIAND(A)' `INTEGER(8) `INTEGER(8)' GNU extension
A'
_See also_:
*note IOR::, *note IEOR::, *note IBITS::, *note IBSET::, *note
IBCLR::, *note NOT::

File: gfortran.info, Node: IANY, Next: IARGC, Prev: IAND, Up: Intrinsic Procedures
9.138 `IANY' -- Bitwise OR of array elements
============================================
_Description_:
Reduces with bitwise OR (inclusive or) the elements of ARRAY along
dimension DIM if the corresponding element in MASK is `TRUE'.
_Standard_:
Fortran 2008 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = IANY(ARRAY[, MASK])'
`RESULT = IANY(ARRAY, DIM[, MASK])'
_Arguments_:
ARRAY Shall be an array of type `INTEGER'
DIM (Optional) shall be a scalar of type `INTEGER'
with a value in the range from 1 to n, where n
equals the rank of ARRAY.
MASK (Optional) shall be of type `LOGICAL' and
either be a scalar or an array of the same
shape as ARRAY.
_Return value_:
The result is of the same type as ARRAY.
If DIM is absent, a scalar with the bitwise OR of all elements in
ARRAY is returned. Otherwise, an array of rank n-1, where n equals
the rank of ARRAY, and a shape similar to that of ARRAY with
dimension DIM dropped is returned.
_Example_:
PROGRAM test_iany
INTEGER(1) :: a(2)
a(1) = b'00100100'
a(2) = b'01101010'
! prints 01101110
PRINT '(b8.8)', IANY(a)
END PROGRAM
_See also_:
*note IPARITY::, *note IALL::, *note IOR::

File: gfortran.info, Node: IARGC, Next: IBCLR, Prev: IANY, Up: Intrinsic Procedures
9.139 `IARGC' -- Get the number of command line arguments
=========================================================
_Description_:
`IARGC' returns the number of arguments passed on the command line
when the containing program was invoked.
This intrinsic routine is provided for backwards compatibility with
GNU Fortran 77. In new code, programmers should consider the use
of the *note COMMAND_ARGUMENT_COUNT:: intrinsic defined by the
Fortran 2003 standard.
_Standard_:
GNU extension
_Class_:
Function
_Syntax_:
`RESULT = IARGC()'
_Arguments_:
None.
_Return value_:
The number of command line arguments, type `INTEGER(4)'.
_Example_:
See *note GETARG::
_See also_:
GNU Fortran 77 compatibility subroutine: *note GETARG::
Fortran 2003 functions and subroutines: *note GET_COMMAND::, *note
GET_COMMAND_ARGUMENT::, *note COMMAND_ARGUMENT_COUNT::

File: gfortran.info, Node: IBCLR, Next: IBITS, Prev: IARGC, Up: Intrinsic Procedures
9.140 `IBCLR' -- Clear bit
==========================
_Description_:
`IBCLR' returns the value of I with the bit at position POS set to
zero.
_Standard_:
Fortran 95 and later, has overloads that are GNU extensions
_Class_:
Elemental function
_Syntax_:
`RESULT = IBCLR(I, POS)'
_Arguments_:
I The type shall be `INTEGER'.
POS The type shall be `INTEGER'.
_Return value_:
The return value is of type `INTEGER' and of the same kind as I.
_Specific names_:
Name Argument Return type Standard
`IBCLR(A)' `INTEGER A' `INTEGER' Fortran 95 and
later
`BBCLR(A)' `INTEGER(1) `INTEGER(1)' GNU extension
A'
`IIBCLR(A)' `INTEGER(2) `INTEGER(2)' GNU extension
A'
`JIBCLR(A)' `INTEGER(4) `INTEGER(4)' GNU extension
A'
`KIBCLR(A)' `INTEGER(8) `INTEGER(8)' GNU extension
A'
_See also_:
*note IBITS::, *note IBSET::, *note IAND::, *note IOR::, *note
IEOR::, *note MVBITS::

File: gfortran.info, Node: IBITS, Next: IBSET, Prev: IBCLR, Up: Intrinsic Procedures
9.141 `IBITS' -- Bit extraction
===============================
_Description_:
`IBITS' extracts a field of length LEN from I, starting from bit
position POS and extending left for LEN bits. The result is
right-justified and the remaining bits are zeroed. The value of
`POS+LEN' must be less than or equal to the value `BIT_SIZE(I)'.
_Standard_:
Fortran 95 and later, has overloads that are GNU extensions
_Class_:
Elemental function
_Syntax_:
`RESULT = IBITS(I, POS, LEN)'
_Arguments_:
I The type shall be `INTEGER'.
POS The type shall be `INTEGER'.
LEN The type shall be `INTEGER'.
_Return value_:
The return value is of type `INTEGER' and of the same kind as I.
_Specific names_:
Name Argument Return type Standard
`IBITS(A)' `INTEGER A' `INTEGER' Fortran 95 and
later
`BBITS(A)' `INTEGER(1) `INTEGER(1)' GNU extension
A'
`IIBITS(A)' `INTEGER(2) `INTEGER(2)' GNU extension
A'
`JIBITS(A)' `INTEGER(4) `INTEGER(4)' GNU extension
A'
`KIBITS(A)' `INTEGER(8) `INTEGER(8)' GNU extension
A'
_See also_:
*note BIT_SIZE::, *note IBCLR::, *note IBSET::, *note IAND::,
*note IOR::, *note IEOR::

File: gfortran.info, Node: IBSET, Next: ICHAR, Prev: IBITS, Up: Intrinsic Procedures
9.142 `IBSET' -- Set bit
========================
_Description_:
`IBSET' returns the value of I with the bit at position POS set to
one.
_Standard_:
Fortran 95 and later, has overloads that are GNU extensions
_Class_:
Elemental function
_Syntax_:
`RESULT = IBSET(I, POS)'
_Arguments_:
I The type shall be `INTEGER'.
POS The type shall be `INTEGER'.
_Return value_:
The return value is of type `INTEGER' and of the same kind as I.
_Specific names_:
Name Argument Return type Standard
`IBSET(A)' `INTEGER A' `INTEGER' Fortran 95 and
later
`BBSET(A)' `INTEGER(1) `INTEGER(1)' GNU extension
A'
`IIBSET(A)' `INTEGER(2) `INTEGER(2)' GNU extension
A'
`JIBSET(A)' `INTEGER(4) `INTEGER(4)' GNU extension
A'
`KIBSET(A)' `INTEGER(8) `INTEGER(8)' GNU extension
A'
_See also_:
*note IBCLR::, *note IBITS::, *note IAND::, *note IOR::, *note
IEOR::, *note MVBITS::

File: gfortran.info, Node: ICHAR, Next: IDATE, Prev: IBSET, Up: Intrinsic Procedures
9.143 `ICHAR' -- Character-to-integer conversion function
=========================================================
_Description_:
`ICHAR(C)' returns the code for the character in the first
character position of `C' in the system's native character set.
The correspondence between characters and their codes is not
necessarily the same across different GNU Fortran implementations.
_Standard_:
Fortran 95 and later, with KIND argument Fortran 2003 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = ICHAR(C [, KIND])'
_Arguments_:
C Shall be a scalar `CHARACTER', with
`INTENT(IN)'
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
_Return value_:
The return value is of type `INTEGER' and of kind KIND. If KIND is
absent, the return value is of default integer kind.
_Example_:
program test_ichar
integer i
i = ichar(' ')
end program test_ichar
_Specific names_:
Name Argument Return type Standard
`ICHAR(C)' `CHARACTER `INTEGER(4)' Fortran 77 and
C' later
_Note_:
No intrinsic exists to convert between a numeric value and a
formatted character string representation - for instance, given the
`CHARACTER' value `'154'', obtaining an `INTEGER' or `REAL' value
with the value 154, or vice versa. Instead, this functionality is
provided by internal-file I/O, as in the following example:
program read_val
integer value
character(len=10) string, string2
string = '154'
! Convert a string to a numeric value
read (string,'(I10)') value
print *, value
! Convert a value to a formatted string
write (string2,'(I10)') value
print *, string2
end program read_val
_See also_:
*note ACHAR::, *note CHAR::, *note IACHAR::

File: gfortran.info, Node: IDATE, Next: IEOR, Prev: ICHAR, Up: Intrinsic Procedures
9.144 `IDATE' -- Get current local time subroutine (day/month/year)
===================================================================
_Description_:
`IDATE(VALUES)' Fills VALUES with the numerical values at the
current local time. The day (in the range 1-31), month (in the
range 1-12), and year appear in elements 1, 2, and 3 of VALUES,
respectively. The year has four significant digits.
This intrinsic routine is provided for backwards compatibility with
GNU Fortran 77. In new code, programmers should consider the use
of the *note DATE_AND_TIME:: intrinsic defined by the Fortran 95
standard.
_Standard_:
GNU extension
_Class_:
Subroutine
_Syntax_:
`CALL IDATE(VALUES)'
_Arguments_:
VALUES The type shall be `INTEGER, DIMENSION(3)' and
the kind shall be the default integer kind.
_Return value_:
Does not return anything.
_Example_:
program test_idate
integer, dimension(3) :: tarray
call idate(tarray)
print *, tarray(1)
print *, tarray(2)
print *, tarray(3)
end program test_idate
_See also_:
*note DATE_AND_TIME::

File: gfortran.info, Node: IEOR, Next: IERRNO, Prev: IDATE, Up: Intrinsic Procedures
9.145 `IEOR' -- Bitwise logical exclusive or
============================================
_Description_:
`IEOR' returns the bitwise Boolean exclusive-OR of I and J.
_Standard_:
Fortran 95 and later, has overloads that are GNU extensions
_Class_:
Elemental function
_Syntax_:
`RESULT = IEOR(I, J)'
_Arguments_:
I The type shall be `INTEGER' or a
boz-literal-constant.
J The type shall be `INTEGER' with the same kind
type parameter as I or a boz-literal-constant.
I and J shall not both be
boz-literal-constants.
_Return value_:
The return type is `INTEGER' with the kind type parameter of the
arguments. A boz-literal-constant is converted to an `INTEGER'
with the kind type parameter of the other argument as-if a call to
*note INT:: occurred.
_Specific names_:
Name Argument Return type Standard
`IEOR(A)' `INTEGER A' `INTEGER' Fortran 95 and
later
`BIEOR(A)' `INTEGER(1) `INTEGER(1)' GNU extension
A'
`IIEOR(A)' `INTEGER(2) `INTEGER(2)' GNU extension
A'
`JIEOR(A)' `INTEGER(4) `INTEGER(4)' GNU extension
A'
`KIEOR(A)' `INTEGER(8) `INTEGER(8)' GNU extension
A'
_See also_:
*note IOR::, *note IAND::, *note IBITS::, *note IBSET::, *note
IBCLR::, *note NOT::

File: gfortran.info, Node: IERRNO, Next: IMAGE_INDEX, Prev: IEOR, Up: Intrinsic Procedures
9.146 `IERRNO' -- Get the last system error number
==================================================
_Description_:
Returns the last system error number, as given by the C `errno'
variable.
_Standard_:
GNU extension
_Class_:
Function
_Syntax_:
`RESULT = IERRNO()'
_Arguments_:
None.
_Return value_:
The return value is of type `INTEGER' and of the default integer
kind.
_See also_:
*note PERROR::

File: gfortran.info, Node: IMAGE_INDEX, Next: INDEX intrinsic, Prev: IERRNO, Up: Intrinsic Procedures
9.147 `IMAGE_INDEX' -- Function that converts a cosubscript to an image index
=============================================================================
_Description_:
Returns the image index belonging to a cosubscript.
_Standard_:
Fortran 2008 and later
_Class_:
Inquiry function.
_Syntax_:
`RESULT = IMAGE_INDEX(COARRAY, SUB)'
_Arguments_: None.
COARRAY Coarray of any type.
SUB default integer rank-1 array of a size equal to
the corank of COARRAY.
_Return value_:
Scalar default integer with the value of the image index which
corresponds to the cosubscripts. For invalid cosubscripts the
result is zero.
_Example_:
INTEGER :: array[2,-1:4,8,*]
! Writes 28 (or 0 if there are fewer than 28 images)
WRITE (*,*) IMAGE_INDEX (array, [2,0,3,1])
_See also_:
*note THIS_IMAGE::, *note NUM_IMAGES::

File: gfortran.info, Node: INDEX intrinsic, Next: INT, Prev: IMAGE_INDEX, Up: Intrinsic Procedures
9.148 `INDEX' -- Position of a substring within a string
========================================================
_Description_:
Returns the position of the start of the first occurrence of string
SUBSTRING as a substring in STRING, counting from one. If
SUBSTRING is not present in STRING, zero is returned. If the BACK
argument is present and true, the return value is the start of the
last occurrence rather than the first.
_Standard_:
Fortran 77 and later, with KIND argument Fortran 2003 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = INDEX(STRING, SUBSTRING [, BACK [, KIND]])'
_Arguments_:
STRING Shall be a scalar `CHARACTER', with
`INTENT(IN)'
SUBSTRING Shall be a scalar `CHARACTER', with
`INTENT(IN)'
BACK (Optional) Shall be a scalar `LOGICAL', with
`INTENT(IN)'
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
_Return value_:
The return value is of type `INTEGER' and of kind KIND. If KIND is
absent, the return value is of default integer kind.
_Specific names_:
Name Argument Return type Standard
`INDEX(STRING,`CHARACTER' `INTEGER(4)' Fortran 77 and
SUBSTRING)' later
_See also_:
*note SCAN::, *note VERIFY::

File: gfortran.info, Node: INT, Next: INT2, Prev: INDEX intrinsic, Up: Intrinsic Procedures
9.149 `INT' -- Convert to integer type
======================================
_Description_:
Convert to integer type
_Standard_:
Fortran 77 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = INT(A [, KIND))'
_Arguments_:
A Shall be of type `INTEGER', `REAL', or
`COMPLEX'.
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
_Return value_:
These functions return a `INTEGER' variable or array under the
following rules:
(A)
If A is of type `INTEGER', `INT(A) = A'
(B)
If A is of type `REAL' and |A| < 1, `INT(A)' equals `0'. If
|A| \geq 1, then `INT(A)' is the integer whose magnitude is
the largest integer that does not exceed the magnitude of A
and whose sign is the same as the sign of A.
(C)
If A is of type `COMPLEX', rule B is applied to the real part
of A.
_Example_:
program test_int
integer :: i = 42
complex :: z = (-3.7, 1.0)
print *, int(i)
print *, int(z), int(z,8)
end program
_Specific names_:
Name Argument Return type Standard
`INT(A)' `REAL(4) A' `INTEGER' Fortran 77 and
later
`IFIX(A)' `REAL(4) A' `INTEGER' Fortran 77 and
later
`IDINT(A)' `REAL(8) A' `INTEGER' Fortran 77 and
later

File: gfortran.info, Node: INT2, Next: INT8, Prev: INT, Up: Intrinsic Procedures
9.150 `INT2' -- Convert to 16-bit integer type
==============================================
_Description_:
Convert to a `KIND=2' integer type. This is equivalent to the
standard `INT' intrinsic with an optional argument of `KIND=2',
and is only included for backwards compatibility.
The `SHORT' intrinsic is equivalent to `INT2'.
_Standard_:
GNU extension
_Class_:
Elemental function
_Syntax_:
`RESULT = INT2(A)'
_Arguments_:
A Shall be of type `INTEGER', `REAL', or
`COMPLEX'.
_Return value_:
The return value is a `INTEGER(2)' variable.
_See also_:
*note INT::, *note INT8::, *note LONG::

File: gfortran.info, Node: INT8, Next: IOR, Prev: INT2, Up: Intrinsic Procedures
9.151 `INT8' -- Convert to 64-bit integer type
==============================================
_Description_:
Convert to a `KIND=8' integer type. This is equivalent to the
standard `INT' intrinsic with an optional argument of `KIND=8',
and is only included for backwards compatibility.
_Standard_:
GNU extension
_Class_:
Elemental function
_Syntax_:
`RESULT = INT8(A)'
_Arguments_:
A Shall be of type `INTEGER', `REAL', or
`COMPLEX'.
_Return value_:
The return value is a `INTEGER(8)' variable.
_See also_:
*note INT::, *note INT2::, *note LONG::

File: gfortran.info, Node: IOR, Next: IPARITY, Prev: INT8, Up: Intrinsic Procedures
9.152 `IOR' -- Bitwise logical or
=================================
_Description_:
`IOR' returns the bitwise Boolean inclusive-OR of I and J.
_Standard_:
Fortran 95 and later, has overloads that are GNU extensions
_Class_:
Elemental function
_Syntax_:
`RESULT = IOR(I, J)'
_Arguments_:
I The type shall be `INTEGER' or a
boz-literal-constant.
J The type shall be `INTEGER' with the same kind
type parameter as I or a boz-literal-constant.
I and J shall not both be
boz-literal-constants.
_Return value_:
The return type is `INTEGER' with the kind type parameter of the
arguments. A boz-literal-constant is converted to an `INTEGER'
with the kind type parameter of the other argument as-if a call to
*note INT:: occurred.
_Specific names_:
Name Argument Return type Standard
`IOR(A)' `INTEGER A' `INTEGER' Fortran 95 and
later
`BIOR(A)' `INTEGER(1) `INTEGER(1)' GNU extension
A'
`IIOR(A)' `INTEGER(2) `INTEGER(2)' GNU extension
A'
`JIOR(A)' `INTEGER(4) `INTEGER(4)' GNU extension
A'
`KIOR(A)' `INTEGER(8) `INTEGER(8)' GNU extension
A'
_See also_:
*note IEOR::, *note IAND::, *note IBITS::, *note IBSET::, *note
IBCLR::, *note NOT::

File: gfortran.info, Node: IPARITY, Next: IRAND, Prev: IOR, Up: Intrinsic Procedures
9.153 `IPARITY' -- Bitwise XOR of array elements
================================================
_Description_:
Reduces with bitwise XOR (exclusive or) the elements of ARRAY along
dimension DIM if the corresponding element in MASK is `TRUE'.
_Standard_:
Fortran 2008 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = IPARITY(ARRAY[, MASK])'
`RESULT = IPARITY(ARRAY, DIM[, MASK])'
_Arguments_:
ARRAY Shall be an array of type `INTEGER'
DIM (Optional) shall be a scalar of type `INTEGER'
with a value in the range from 1 to n, where n
equals the rank of ARRAY.
MASK (Optional) shall be of type `LOGICAL' and
either be a scalar or an array of the same
shape as ARRAY.
_Return value_:
The result is of the same type as ARRAY.
If DIM is absent, a scalar with the bitwise XOR of all elements in
ARRAY is returned. Otherwise, an array of rank n-1, where n equals
the rank of ARRAY, and a shape similar to that of ARRAY with
dimension DIM dropped is returned.
_Example_:
PROGRAM test_iparity
INTEGER(1) :: a(2)
a(1) = b'00100100'
a(2) = b'01101010'
! prints 01001110
PRINT '(b8.8)', IPARITY(a)
END PROGRAM
_See also_:
*note IANY::, *note IALL::, *note IEOR::, *note PARITY::

File: gfortran.info, Node: IRAND, Next: IS_CONTIGUOUS, Prev: IPARITY, Up: Intrinsic Procedures
9.154 `IRAND' -- Integer pseudo-random number
=============================================
_Description_:
`IRAND(FLAG)' returns a pseudo-random number from a uniform
distribution between 0 and a system-dependent limit (which is in
most cases 2147483647). If FLAG is 0, the next number in the
current sequence is returned; if FLAG is 1, the generator is
restarted by `CALL SRAND(0)'; if FLAG has any other value, it is
used as a new seed with `SRAND'.
This intrinsic routine is provided for backwards compatibility with
GNU Fortran 77. It implements a simple modulo generator as provided
by `g77'. For new code, one should consider the use of *note
RANDOM_NUMBER:: as it implements a superior algorithm.
_Standard_:
GNU extension
_Class_:
Function
_Syntax_:
`RESULT = IRAND(I)'
_Arguments_:
I Shall be a scalar `INTEGER' of kind 4.
_Return value_:
The return value is of `INTEGER(kind=4)' type.
_Example_:
program test_irand
integer,parameter :: seed = 86456
call srand(seed)
print *, irand(), irand(), irand(), irand()
print *, irand(seed), irand(), irand(), irand()
end program test_irand

File: gfortran.info, Node: IS_CONTIGUOUS, Next: IS_IOSTAT_END, Prev: IRAND, Up: Intrinsic Procedures
9.155 `IS_CONTIGUOUS' -- Test whether an array is contiguous
============================================================
_Description_:
`IS_CONTIGUOUS' tests whether an array is contiguous.
_Standard_:
Fortran 2008 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = IS_CONTIGUOUS(ARRAY)'
_Arguments_:
ARRAY Shall be an array of any type.
_Return value_:
Returns a `LOGICAL' of the default kind, which `.TRUE.' if ARRAY
is contiguous and false otherwise.
_Example_:
program test
integer :: a(10)
a = [1,2,3,4,5,6,7,8,9,10]
call sub (a) ! every element, is contiguous
call sub (a(::2)) ! every other element, is noncontiguous
contains
subroutine sub (x)
integer :: x(:)
if (is_contiguous (x)) then
write (*,*) 'X is contiguous'
else
write (*,*) 'X is not contiguous'
end if
end subroutine sub
end program test

File: gfortran.info, Node: IS_IOSTAT_END, Next: IS_IOSTAT_EOR, Prev: IS_CONTIGUOUS, Up: Intrinsic Procedures
9.156 `IS_IOSTAT_END' -- Test for end-of-file value
===================================================
_Description_:
`IS_IOSTAT_END' tests whether an variable has the value of the I/O
status "end of file". The function is equivalent to comparing the
variable with the `IOSTAT_END' parameter of the intrinsic module
`ISO_FORTRAN_ENV'.
_Standard_:
Fortran 2003 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = IS_IOSTAT_END(I)'
_Arguments_:
I Shall be of the type `INTEGER'.
_Return value_:
Returns a `LOGICAL' of the default kind, which `.TRUE.' if I has
the value which indicates an end of file condition for `IOSTAT='
specifiers, and is `.FALSE.' otherwise.
_Example_:
PROGRAM iostat
IMPLICIT NONE
INTEGER :: stat, i
OPEN(88, FILE='test.dat')
READ(88, *, IOSTAT=stat) i
IF(IS_IOSTAT_END(stat)) STOP 'END OF FILE'
END PROGRAM

File: gfortran.info, Node: IS_IOSTAT_EOR, Next: ISATTY, Prev: IS_IOSTAT_END, Up: Intrinsic Procedures
9.157 `IS_IOSTAT_EOR' -- Test for end-of-record value
=====================================================
_Description_:
`IS_IOSTAT_EOR' tests whether an variable has the value of the I/O
status "end of record". The function is equivalent to comparing the
variable with the `IOSTAT_EOR' parameter of the intrinsic module
`ISO_FORTRAN_ENV'.
_Standard_:
Fortran 2003 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = IS_IOSTAT_EOR(I)'
_Arguments_:
I Shall be of the type `INTEGER'.
_Return value_:
Returns a `LOGICAL' of the default kind, which `.TRUE.' if I has
the value which indicates an end of file condition for `IOSTAT='
specifiers, and is `.FALSE.' otherwise.
_Example_:
PROGRAM iostat
IMPLICIT NONE
INTEGER :: stat, i(50)
OPEN(88, FILE='test.dat', FORM='UNFORMATTED')
READ(88, IOSTAT=stat) i
IF(IS_IOSTAT_EOR(stat)) STOP 'END OF RECORD'
END PROGRAM

File: gfortran.info, Node: ISATTY, Next: ISHFT, Prev: IS_IOSTAT_EOR, Up: Intrinsic Procedures
9.158 `ISATTY' -- Whether a unit is a terminal device.
======================================================
_Description_:
Determine whether a unit is connected to a terminal device.
_Standard_:
GNU extension
_Class_:
Function
_Syntax_:
`RESULT = ISATTY(UNIT)'
_Arguments_:
UNIT Shall be a scalar `INTEGER'.
_Return value_:
Returns `.TRUE.' if the UNIT is connected to a terminal device,
`.FALSE.' otherwise.
_Example_:
PROGRAM test_isatty
INTEGER(kind=1) :: unit
DO unit = 1, 10
write(*,*) isatty(unit=unit)
END DO
END PROGRAM
_See also_:
*note TTYNAM::

File: gfortran.info, Node: ISHFT, Next: ISHFTC, Prev: ISATTY, Up: Intrinsic Procedures
9.159 `ISHFT' -- Shift bits
===========================
_Description_:
`ISHFT' returns a value corresponding to I with all of the bits
shifted SHIFT places. A value of SHIFT greater than zero
corresponds to a left shift, a value of zero corresponds to no
shift, and a value less than zero corresponds to a right shift.
If the absolute value of SHIFT is greater than `BIT_SIZE(I)', the
value is undefined. Bits shifted out from the left end or right
end are lost; zeros are shifted in from the opposite end.
_Standard_:
Fortran 95 and later, has overloads that are GNU extensions
_Class_:
Elemental function
_Syntax_:
`RESULT = ISHFT(I, SHIFT)'
_Arguments_:
I The type shall be `INTEGER'.
SHIFT The type shall be `INTEGER'.
_Return value_:
The return value is of type `INTEGER' and of the same kind as I.
_Specific names_:
Name Argument Return type Standard
`ISHFT(A)' `INTEGER A' `INTEGER' Fortran 95 and
later
`BSHFT(A)' `INTEGER(1) `INTEGER(1)' GNU extension
A'
`IISHFT(A)' `INTEGER(2) `INTEGER(2)' GNU extension
A'
`JISHFT(A)' `INTEGER(4) `INTEGER(4)' GNU extension
A'
`KISHFT(A)' `INTEGER(8) `INTEGER(8)' GNU extension
A'
_See also_:
*note ISHFTC::

File: gfortran.info, Node: ISHFTC, Next: ISNAN, Prev: ISHFT, Up: Intrinsic Procedures
9.160 `ISHFTC' -- Shift bits circularly
=======================================
_Description_:
`ISHFTC' returns a value corresponding to I with the rightmost
SIZE bits shifted circularly SHIFT places; that is, bits shifted
out one end are shifted into the opposite end. A value of SHIFT
greater than zero corresponds to a left shift, a value of zero
corresponds to no shift, and a value less than zero corresponds to
a right shift. The absolute value of SHIFT must be less than
SIZE. If the SIZE argument is omitted, it is taken to be
equivalent to `BIT_SIZE(I)'.
_Standard_:
Fortran 95 and later, has overloads that are GNU extensions
_Class_:
Elemental function
_Syntax_:
`RESULT = ISHFTC(I, SHIFT [, SIZE])'
_Arguments_:
I The type shall be `INTEGER'.
SHIFT The type shall be `INTEGER'.
SIZE (Optional) The type shall be `INTEGER'; the
value must be greater than zero and less than
or equal to `BIT_SIZE(I)'.
_Return value_:
The return value is of type `INTEGER' and of the same kind as I.
_Specific names_:
Name Argument Return type Standard
`ISHFTC(A)' `INTEGER A' `INTEGER' Fortran 95 and
later
`BSHFTC(A)' `INTEGER(1) `INTEGER(1)' GNU extension
A'
`IISHFTC(A)' `INTEGER(2) `INTEGER(2)' GNU extension
A'
`JISHFTC(A)' `INTEGER(4) `INTEGER(4)' GNU extension
A'
`KISHFTC(A)' `INTEGER(8) `INTEGER(8)' GNU extension
A'
_See also_:
*note ISHFT::

File: gfortran.info, Node: ISNAN, Next: ITIME, Prev: ISHFTC, Up: Intrinsic Procedures
9.161 `ISNAN' -- Test for a NaN
===============================
_Description_:
`ISNAN' tests whether a floating-point value is an IEEE
Not-a-Number (NaN).
_Standard_:
GNU extension
_Class_:
Elemental function
_Syntax_:
`ISNAN(X)'
_Arguments_:
X Variable of the type `REAL'.
_Return value_:
Returns a default-kind `LOGICAL'. The returned value is `TRUE' if
X is a NaN and `FALSE' otherwise.
_Example_:
program test_nan
implicit none
real :: x
x = -1.0
x = sqrt(x)
if (isnan(x)) stop '"x" is a NaN'
end program test_nan

File: gfortran.info, Node: ITIME, Next: KILL, Prev: ISNAN, Up: Intrinsic Procedures
9.162 `ITIME' -- Get current local time subroutine (hour/minutes/seconds)
=========================================================================
_Description_:
`ITIME(VALUES)' Fills VALUES with the numerical values at the
current local time. The hour (in the range 1-24), minute (in the
range 1-60), and seconds (in the range 1-60) appear in elements 1,
2, and 3 of VALUES, respectively.
This intrinsic routine is provided for backwards compatibility with
GNU Fortran 77. In new code, programmers should consider the use
of the *note DATE_AND_TIME:: intrinsic defined by the Fortran 95
standard.
_Standard_:
GNU extension
_Class_:
Subroutine
_Syntax_:
`CALL ITIME(VALUES)'
_Arguments_:
VALUES The type shall be `INTEGER, DIMENSION(3)' and
the kind shall be the default integer kind.
_Return value_:
Does not return anything.
_Example_:
program test_itime
integer, dimension(3) :: tarray
call itime(tarray)
print *, tarray(1)
print *, tarray(2)
print *, tarray(3)
end program test_itime
_See also_:
*note DATE_AND_TIME::

File: gfortran.info, Node: KILL, Next: KIND, Prev: ITIME, Up: Intrinsic Procedures
9.163 `KILL' -- Send a signal to a process
==========================================
_Description_:
_Standard_:
Sends the signal specified by SIG to the process PID. See
`kill(2)'.
This intrinsic is provided in both subroutine and function forms;
however, only one form can be used in any given program unit.
_Class_:
Subroutine, function
_Syntax_:
`CALL KILL(PID, SIG [, STATUS])'
`STATUS = KILL(PID, SIG)'
_Arguments_:
PID Shall be a scalar `INTEGER' with `INTENT(IN)'.
SIG Shall be a scalar `INTEGER' with `INTENT(IN)'.
STATUS [Subroutine](Optional) Shall be a scalar
`INTEGER'. Returns 0 on success; otherwise a
system-specific error code is returned.
STATUS [Function] The kind type parameter is that of
`pid'. Returns 0 on success; otherwise a
system-specific error code is returned.
_See also_:
*note ABORT::, *note EXIT::

File: gfortran.info, Node: KIND, Next: LBOUND, Prev: KILL, Up: Intrinsic Procedures
9.164 `KIND' -- Kind of an entity
=================================
_Description_:
`KIND(X)' returns the kind value of the entity X.
_Standard_:
Fortran 95 and later
_Class_:
Inquiry function
_Syntax_:
`K = KIND(X)'
_Arguments_:
X Shall be of type `LOGICAL', `INTEGER', `REAL',
`COMPLEX' or `CHARACTER'.
_Return value_:
The return value is a scalar of type `INTEGER' and of the default
integer kind.
_Example_:
program test_kind
integer,parameter :: kc = kind(' ')
integer,parameter :: kl = kind(.true.)
print *, "The default character kind is ", kc
print *, "The default logical kind is ", kl
end program test_kind

File: gfortran.info, Node: LBOUND, Next: LCOBOUND, Prev: KIND, Up: Intrinsic Procedures
9.165 `LBOUND' -- Lower dimension bounds of an array
====================================================
_Description_:
Returns the lower bounds of an array, or a single lower bound
along the DIM dimension.
_Standard_:
Fortran 95 and later, with KIND argument Fortran 2003 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = LBOUND(ARRAY [, DIM [, KIND]])'
_Arguments_:
ARRAY Shall be an array, of any type.
DIM (Optional) Shall be a scalar `INTEGER'.
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
_Return value_:
The return value is of type `INTEGER' and of kind KIND. If KIND is
absent, the return value is of default integer kind. If DIM is
absent, the result is an array of the lower bounds of ARRAY. If
DIM is present, the result is a scalar corresponding to the lower
bound of the array along that dimension. If ARRAY is an
expression rather than a whole array or array structure component,
or if it has a zero extent along the relevant dimension, the lower
bound is taken to be 1.
_See also_:
*note UBOUND::, *note LCOBOUND::

File: gfortran.info, Node: LCOBOUND, Next: LEADZ, Prev: LBOUND, Up: Intrinsic Procedures
9.166 `LCOBOUND' -- Lower codimension bounds of an array
========================================================
_Description_:
Returns the lower bounds of a coarray, or a single lower cobound
along the DIM codimension.
_Standard_:
Fortran 2008 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = LCOBOUND(COARRAY [, DIM [, KIND]])'
_Arguments_:
ARRAY Shall be an coarray, of any type.
DIM (Optional) Shall be a scalar `INTEGER'.
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
_Return value_:
The return value is of type `INTEGER' and of kind KIND. If KIND is
absent, the return value is of default integer kind. If DIM is
absent, the result is an array of the lower cobounds of COARRAY.
If DIM is present, the result is a scalar corresponding to the
lower cobound of the array along that codimension.
_See also_:
*note UCOBOUND::, *note LBOUND::

File: gfortran.info, Node: LEADZ, Next: LEN, Prev: LCOBOUND, Up: Intrinsic Procedures
9.167 `LEADZ' -- Number of leading zero bits of an integer
==========================================================
_Description_:
`LEADZ' returns the number of leading zero bits of an integer.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = LEADZ(I)'
_Arguments_:
I Shall be of type `INTEGER'.
_Return value_:
The type of the return value is the default `INTEGER'. If all the
bits of `I' are zero, the result value is `BIT_SIZE(I)'.
_Example_:
PROGRAM test_leadz
WRITE (*,*) BIT_SIZE(1) ! prints 32
WRITE (*,*) LEADZ(1) ! prints 31
END PROGRAM
_See also_:
*note BIT_SIZE::, *note TRAILZ::, *note POPCNT::, *note POPPAR::

File: gfortran.info, Node: LEN, Next: LEN_TRIM, Prev: LEADZ, Up: Intrinsic Procedures
9.168 `LEN' -- Length of a character entity
===========================================
_Description_:
Returns the length of a character string. If STRING is an array,
the length of an element of STRING is returned. Note that STRING
need not be defined when this intrinsic is invoked, since only the
length, not the content, of STRING is needed.
_Standard_:
Fortran 77 and later, with KIND argument Fortran 2003 and later
_Class_:
Inquiry function
_Syntax_:
`L = LEN(STRING [, KIND])'
_Arguments_:
STRING Shall be a scalar or array of type
`CHARACTER', with `INTENT(IN)'
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
_Return value_:
The return value is of type `INTEGER' and of kind KIND. If KIND is
absent, the return value is of default integer kind.
_Specific names_:
Name Argument Return type Standard
`LEN(STRING)' `CHARACTER' `INTEGER' Fortran 77 and
later
_See also_:
*note LEN_TRIM::, *note ADJUSTL::, *note ADJUSTR::

File: gfortran.info, Node: LEN_TRIM, Next: LGE, Prev: LEN, Up: Intrinsic Procedures
9.169 `LEN_TRIM' -- Length of a character entity without trailing blank characters
==================================================================================
_Description_:
Returns the length of a character string, ignoring any trailing
blanks.
_Standard_:
Fortran 95 and later, with KIND argument Fortran 2003 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = LEN_TRIM(STRING [, KIND])'
_Arguments_:
STRING Shall be a scalar of type `CHARACTER', with
`INTENT(IN)'
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
_Return value_:
The return value is of type `INTEGER' and of kind KIND. If KIND is
absent, the return value is of default integer kind.
_See also_:
*note LEN::, *note ADJUSTL::, *note ADJUSTR::

File: gfortran.info, Node: LGE, Next: LGT, Prev: LEN_TRIM, Up: Intrinsic Procedures
9.170 `LGE' -- Lexical greater than or equal
============================================
_Description_:
Determines whether one string is lexically greater than or equal to
another string, where the two strings are interpreted as containing
ASCII character codes. If the String A and String B are not the
same length, the shorter is compared as if spaces were appended to
it to form a value that has the same length as the longer.
In general, the lexical comparison intrinsics `LGE', `LGT', `LLE',
and `LLT' differ from the corresponding intrinsic operators
`.GE.', `.GT.', `.LE.', and `.LT.', in that the latter use the
processor's character ordering (which is not ASCII on some
targets), whereas the former always use the ASCII ordering.
_Standard_:
Fortran 77 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = LGE(STRING_A, STRING_B)'
_Arguments_:
STRING_A Shall be of default `CHARACTER' type.
STRING_B Shall be of default `CHARACTER' type.
_Return value_:
Returns `.TRUE.' if `STRING_A >= STRING_B', and `.FALSE.'
otherwise, based on the ASCII ordering.
_Specific names_:
Name Argument Return type Standard
`LGE(STRING_A,`CHARACTER' `LOGICAL' Fortran 77 and
STRING_B)' later
_See also_:
*note LGT::, *note LLE::, *note LLT::

File: gfortran.info, Node: LGT, Next: LINK, Prev: LGE, Up: Intrinsic Procedures
9.171 `LGT' -- Lexical greater than
===================================
_Description_:
Determines whether one string is lexically greater than another
string, where the two strings are interpreted as containing ASCII
character codes. If the String A and String B are not the same
length, the shorter is compared as if spaces were appended to it
to form a value that has the same length as the longer.
In general, the lexical comparison intrinsics `LGE', `LGT', `LLE',
and `LLT' differ from the corresponding intrinsic operators
`.GE.', `.GT.', `.LE.', and `.LT.', in that the latter use the
processor's character ordering (which is not ASCII on some
targets), whereas the former always use the ASCII ordering.
_Standard_:
Fortran 77 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = LGT(STRING_A, STRING_B)'
_Arguments_:
STRING_A Shall be of default `CHARACTER' type.
STRING_B Shall be of default `CHARACTER' type.
_Return value_:
Returns `.TRUE.' if `STRING_A > STRING_B', and `.FALSE.'
otherwise, based on the ASCII ordering.
_Specific names_:
Name Argument Return type Standard
`LGT(STRING_A,`CHARACTER' `LOGICAL' Fortran 77 and
STRING_B)' later
_See also_:
*note LGE::, *note LLE::, *note LLT::

File: gfortran.info, Node: LINK, Next: LLE, Prev: LGT, Up: Intrinsic Procedures
9.172 `LINK' -- Create a hard link
==================================
_Description_:
Makes a (hard) link from file PATH1 to PATH2. A null character
(`CHAR(0)') can be used to mark the end of the names in PATH1 and
PATH2; otherwise, trailing blanks in the file names are ignored.
If the STATUS argument is supplied, it contains 0 on success or a
nonzero error code upon return; see `link(2)'.
This intrinsic is provided in both subroutine and function forms;
however, only one form can be used in any given program unit.
_Standard_:
GNU extension
_Class_:
Subroutine, function
_Syntax_:
`CALL LINK(PATH1, PATH2 [, STATUS])'
`STATUS = LINK(PATH1, PATH2)'
_Arguments_:
PATH1 Shall be of default `CHARACTER' type.
PATH2 Shall be of default `CHARACTER' type.
STATUS (Optional) Shall be of default `INTEGER' type.
_See also_:
*note SYMLNK::, *note UNLINK::

File: gfortran.info, Node: LLE, Next: LLT, Prev: LINK, Up: Intrinsic Procedures
9.173 `LLE' -- Lexical less than or equal
=========================================
_Description_:
Determines whether one string is lexically less than or equal to
another string, where the two strings are interpreted as
containing ASCII character codes. If the String A and String B
are not the same length, the shorter is compared as if spaces were
appended to it to form a value that has the same length as the
longer.
In general, the lexical comparison intrinsics `LGE', `LGT', `LLE',
and `LLT' differ from the corresponding intrinsic operators
`.GE.', `.GT.', `.LE.', and `.LT.', in that the latter use the
processor's character ordering (which is not ASCII on some
targets), whereas the former always use the ASCII ordering.
_Standard_:
Fortran 77 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = LLE(STRING_A, STRING_B)'
_Arguments_:
STRING_A Shall be of default `CHARACTER' type.
STRING_B Shall be of default `CHARACTER' type.
_Return value_:
Returns `.TRUE.' if `STRING_A <= STRING_B', and `.FALSE.'
otherwise, based on the ASCII ordering.
_Specific names_:
Name Argument Return type Standard
`LLE(STRING_A,`CHARACTER' `LOGICAL' Fortran 77 and
STRING_B)' later
_See also_:
*note LGE::, *note LGT::, *note LLT::

File: gfortran.info, Node: LLT, Next: LNBLNK, Prev: LLE, Up: Intrinsic Procedures
9.174 `LLT' -- Lexical less than
================================
_Description_:
Determines whether one string is lexically less than another
string, where the two strings are interpreted as containing ASCII
character codes. If the String A and String B are not the same
length, the shorter is compared as if spaces were appended to it
to form a value that has the same length as the longer.
In general, the lexical comparison intrinsics `LGE', `LGT', `LLE',
and `LLT' differ from the corresponding intrinsic operators
`.GE.', `.GT.', `.LE.', and `.LT.', in that the latter use the
processor's character ordering (which is not ASCII on some
targets), whereas the former always use the ASCII ordering.
_Standard_:
Fortran 77 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = LLT(STRING_A, STRING_B)'
_Arguments_:
STRING_A Shall be of default `CHARACTER' type.
STRING_B Shall be of default `CHARACTER' type.
_Return value_:
Returns `.TRUE.' if `STRING_A < STRING_B', and `.FALSE.'
otherwise, based on the ASCII ordering.
_Specific names_:
Name Argument Return type Standard
`LLT(STRING_A,`CHARACTER' `LOGICAL' Fortran 77 and
STRING_B)' later
_See also_:
*note LGE::, *note LGT::, *note LLE::

File: gfortran.info, Node: LNBLNK, Next: LOC, Prev: LLT, Up: Intrinsic Procedures
9.175 `LNBLNK' -- Index of the last non-blank character in a string
===================================================================
_Description_:
Returns the length of a character string, ignoring any trailing
blanks. This is identical to the standard `LEN_TRIM' intrinsic,
and is only included for backwards compatibility.
_Standard_:
GNU extension
_Class_:
Elemental function
_Syntax_:
`RESULT = LNBLNK(STRING)'
_Arguments_:
STRING Shall be a scalar of type `CHARACTER', with
`INTENT(IN)'
_Return value_:
The return value is of `INTEGER(kind=4)' type.
_See also_:
*note INDEX intrinsic::, *note LEN_TRIM::

File: gfortran.info, Node: LOC, Next: LOG, Prev: LNBLNK, Up: Intrinsic Procedures
9.176 `LOC' -- Returns the address of a variable
================================================
_Description_:
`LOC(X)' returns the address of X as an integer.
_Standard_:
GNU extension
_Class_:
Inquiry function
_Syntax_:
`RESULT = LOC(X)'
_Arguments_:
X Variable of any type.
_Return value_:
The return value is of type `INTEGER', with a `KIND' corresponding
to the size (in bytes) of a memory address on the target machine.
_Example_:
program test_loc
integer :: i
real :: r
i = loc(r)
print *, i
end program test_loc

File: gfortran.info, Node: LOG, Next: LOG10, Prev: LOC, Up: Intrinsic Procedures
9.177 `LOG' -- Natural logarithm function
=========================================
_Description_:
`LOG(X)' computes the natural logarithm of X, i.e. the logarithm
to the base e.
_Standard_:
Fortran 77 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = LOG(X)'
_Arguments_:
X The type shall be `REAL' or `COMPLEX'.
_Return value_:
The return value is of type `REAL' or `COMPLEX'. The kind type
parameter is the same as X. If X is `COMPLEX', the imaginary part
\omega is in the range -\pi < \omega \leq \pi.
_Example_:
program test_log
real(8) :: x = 2.7182818284590451_8
complex :: z = (1.0, 2.0)
x = log(x) ! will yield (approximately) 1
z = log(z)
end program test_log
_Specific names_:
Name Argument Return type Standard
`ALOG(X)' `REAL(4) X' `REAL(4)' f95, gnu
`DLOG(X)' `REAL(8) X' `REAL(8)' f95, gnu
`CLOG(X)' `COMPLEX(4) `COMPLEX(4)' f95, gnu
X'
`ZLOG(X)' `COMPLEX(8) `COMPLEX(8)' f95, gnu
X'
`CDLOG(X)' `COMPLEX(8) `COMPLEX(8)' f95, gnu
X'

File: gfortran.info, Node: LOG10, Next: LOG_GAMMA, Prev: LOG, Up: Intrinsic Procedures
9.178 `LOG10' -- Base 10 logarithm function
===========================================
_Description_:
`LOG10(X)' computes the base 10 logarithm of X.
_Standard_:
Fortran 77 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = LOG10(X)'
_Arguments_:
X The type shall be `REAL'.
_Return value_:
The return value is of type `REAL' or `COMPLEX'. The kind type
parameter is the same as X.
_Example_:
program test_log10
real(8) :: x = 10.0_8
x = log10(x)
end program test_log10
_Specific names_:
Name Argument Return type Standard
`ALOG10(X)' `REAL(4) X' `REAL(4)' Fortran 95 and
later
`DLOG10(X)' `REAL(8) X' `REAL(8)' Fortran 95 and
later

File: gfortran.info, Node: LOG_GAMMA, Next: LOGICAL, Prev: LOG10, Up: Intrinsic Procedures
9.179 `LOG_GAMMA' -- Logarithm of the Gamma function
====================================================
_Description_:
`LOG_GAMMA(X)' computes the natural logarithm of the absolute value
of the Gamma (\Gamma) function.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`X = LOG_GAMMA(X)'
_Arguments_:
X Shall be of type `REAL' and neither zero nor a
negative integer.
_Return value_:
The return value is of type `REAL' of the same kind as X.
_Example_:
program test_log_gamma
real :: x = 1.0
x = lgamma(x) ! returns 0.0
end program test_log_gamma
_Specific names_:
Name Argument Return type Standard
`LGAMMA(X)' `REAL(4) X' `REAL(4)' GNU Extension
`ALGAMA(X)' `REAL(4) X' `REAL(4)' GNU Extension
`DLGAMA(X)' `REAL(8) X' `REAL(8)' GNU Extension
_See also_:
Gamma function: *note GAMMA::

File: gfortran.info, Node: LOGICAL, Next: LONG, Prev: LOG_GAMMA, Up: Intrinsic Procedures
9.180 `LOGICAL' -- Convert to logical type
==========================================
_Description_:
Converts one kind of `LOGICAL' variable to another.
_Standard_:
Fortran 95 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = LOGICAL(L [, KIND])'
_Arguments_:
L The type shall be `LOGICAL'.
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
_Return value_:
The return value is a `LOGICAL' value equal to L, with a kind
corresponding to KIND, or of the default logical kind if KIND is
not given.
_See also_:
*note INT::, *note REAL::, *note CMPLX::

File: gfortran.info, Node: LONG, Next: LSHIFT, Prev: LOGICAL, Up: Intrinsic Procedures
9.181 `LONG' -- Convert to integer type
=======================================
_Description_:
Convert to a `KIND=4' integer type, which is the same size as a C
`long' integer. This is equivalent to the standard `INT'
intrinsic with an optional argument of `KIND=4', and is only
included for backwards compatibility.
_Standard_:
GNU extension
_Class_:
Elemental function
_Syntax_:
`RESULT = LONG(A)'
_Arguments_:
A Shall be of type `INTEGER', `REAL', or
`COMPLEX'.
_Return value_:
The return value is a `INTEGER(4)' variable.
_See also_:
*note INT::, *note INT2::, *note INT8::

File: gfortran.info, Node: LSHIFT, Next: LSTAT, Prev: LONG, Up: Intrinsic Procedures
9.182 `LSHIFT' -- Left shift bits
=================================
_Description_:
`LSHIFT' returns a value corresponding to I with all of the bits
shifted left by SHIFT places. SHIFT shall be nonnegative and less
than or equal to `BIT_SIZE(I)', otherwise the result value is
undefined. Bits shifted out from the left end are lost; zeros are
shifted in from the opposite end.
This function has been superseded by the `ISHFT' intrinsic, which
is standard in Fortran 95 and later, and the `SHIFTL' intrinsic,
which is standard in Fortran 2008 and later.
_Standard_:
GNU extension
_Class_:
Elemental function
_Syntax_:
`RESULT = LSHIFT(I, SHIFT)'
_Arguments_:
I The type shall be `INTEGER'.
SHIFT The type shall be `INTEGER'.
_Return value_:
The return value is of type `INTEGER' and of the same kind as I.
_See also_:
*note ISHFT::, *note ISHFTC::, *note RSHIFT::, *note SHIFTA::,
*note SHIFTL::, *note SHIFTR::

File: gfortran.info, Node: LSTAT, Next: LTIME, Prev: LSHIFT, Up: Intrinsic Procedures
9.183 `LSTAT' -- Get file status
================================
_Description_:
`LSTAT' is identical to *note STAT::, except that if path is a
symbolic link, then the link itself is statted, not the file that
it refers to.
The elements in `VALUES' are the same as described by *note STAT::.
This intrinsic is provided in both subroutine and function forms;
however, only one form can be used in any given program unit.
_Standard_:
GNU extension
_Class_:
Subroutine, function
_Syntax_:
`CALL LSTAT(NAME, VALUES [, STATUS])'
`STATUS = LSTAT(NAME, VALUES)'
_Arguments_:
NAME The type shall be `CHARACTER' of the default
kind, a valid path within the file system.
VALUES The type shall be `INTEGER(4), DIMENSION(13)'.
STATUS (Optional) status flag of type `INTEGER(4)'.
Returns 0 on success and a system specific
error code otherwise.
_Example_:
See *note STAT:: for an example.
_See also_:
To stat an open file: *note FSTAT::, to stat a file: *note STAT::

File: gfortran.info, Node: LTIME, Next: MALLOC, Prev: LSTAT, Up: Intrinsic Procedures
9.184 `LTIME' -- Convert time to local time info
================================================
_Description_:
Given a system time value TIME (as provided by the *note TIME::
intrinsic), fills VALUES with values extracted from it appropriate
to the local time zone using `localtime(3)'.
This intrinsic routine is provided for backwards compatibility with
GNU Fortran 77. In new code, programmers should consider the use
of the *note DATE_AND_TIME:: intrinsic defined by the Fortran 95
standard.
_Standard_:
GNU extension
_Class_:
Subroutine
_Syntax_:
`CALL LTIME(TIME, VALUES)'
_Arguments_:
TIME An `INTEGER' scalar expression corresponding
to a system time, with `INTENT(IN)'.
VALUES A default `INTEGER' array with 9 elements,
with `INTENT(OUT)'.
_Return value_:
The elements of VALUES are assigned as follows:
1. Seconds after the minute, range 0-59 or 0-61 to allow for leap
seconds
2. Minutes after the hour, range 0-59
3. Hours past midnight, range 0-23
4. Day of month, range 1-31
5. Number of months since January, range 0-11
6. Years since 1900
7. Number of days since Sunday, range 0-6
8. Days since January 1, range 0-365
9. Daylight savings indicator: positive if daylight savings is in
effect, zero if not, and negative if the information is not
available.
_See also_:
*note DATE_AND_TIME::, *note CTIME::, *note GMTIME::, *note
TIME::, *note TIME8::

File: gfortran.info, Node: MALLOC, Next: MASKL, Prev: LTIME, Up: Intrinsic Procedures
9.185 `MALLOC' -- Allocate dynamic memory
=========================================
_Description_:
`MALLOC(SIZE)' allocates SIZE bytes of dynamic memory and returns
the address of the allocated memory. The `MALLOC' intrinsic is an
extension intended to be used with Cray pointers, and is provided
in GNU Fortran to allow the user to compile legacy code. For new
code using Fortran 95 pointers, the memory allocation intrinsic is
`ALLOCATE'.
_Standard_:
GNU extension
_Class_:
Function
_Syntax_:
`PTR = MALLOC(SIZE)'
_Arguments_:
SIZE The type shall be `INTEGER'.
_Return value_:
The return value is of type `INTEGER(K)', with K such that
variables of type `INTEGER(K)' have the same size as C pointers
(`sizeof(void *)').
_Example_:
The following example demonstrates the use of `MALLOC' and `FREE'
with Cray pointers.
program test_malloc
implicit none
integer i
real*8 x(*), z
pointer(ptr_x,x)
ptr_x = malloc(20*8)
do i = 1, 20
x(i) = sqrt(1.0d0 / i)
end do
z = 0
do i = 1, 20
z = z + x(i)
print *, z
end do
call free(ptr_x)
end program test_malloc
_See also_:
*note FREE::

File: gfortran.info, Node: MASKL, Next: MASKR, Prev: MALLOC, Up: Intrinsic Procedures
9.186 `MASKL' -- Left justified mask
====================================
_Description_:
`MASKL(I[, KIND])' has its leftmost I bits set to 1, and the
remaining bits set to 0.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = MASKL(I[, KIND])'
_Arguments_:
I Shall be of type `INTEGER'.
KIND Shall be a scalar constant expression of type
`INTEGER'.
_Return value_:
The return value is of type `INTEGER'. If KIND is present, it
specifies the kind value of the return type; otherwise, it is of
the default integer kind.
_See also_:
*note MASKR::

File: gfortran.info, Node: MASKR, Next: MATMUL, Prev: MASKL, Up: Intrinsic Procedures
9.187 `MASKR' -- Right justified mask
=====================================
_Description_:
`MASKL(I[, KIND])' has its rightmost I bits set to 1, and the
remaining bits set to 0.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = MASKR(I[, KIND])'
_Arguments_:
I Shall be of type `INTEGER'.
KIND Shall be a scalar constant expression of type
`INTEGER'.
_Return value_:
The return value is of type `INTEGER'. If KIND is present, it
specifies the kind value of the return type; otherwise, it is of
the default integer kind.
_See also_:
*note MASKL::

File: gfortran.info, Node: MATMUL, Next: MAX, Prev: MASKR, Up: Intrinsic Procedures
9.188 `MATMUL' -- matrix multiplication
=======================================
_Description_:
Performs a matrix multiplication on numeric or logical arguments.
_Standard_:
Fortran 95 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = MATMUL(MATRIX_A, MATRIX_B)'
_Arguments_:
MATRIX_A An array of `INTEGER', `REAL', `COMPLEX', or
`LOGICAL' type, with a rank of one or two.
MATRIX_B An array of `INTEGER', `REAL', or `COMPLEX'
type if MATRIX_A is of a numeric type;
otherwise, an array of `LOGICAL' type. The
rank shall be one or two, and the first (or
only) dimension of MATRIX_B shall be equal to
the last (or only) dimension of MATRIX_A.
MATRIX_A and MATRIX_B shall not both be rank
one arrays.
_Return value_:
The matrix product of MATRIX_A and MATRIX_B. The type and kind of
the result follow the usual type and kind promotion rules, as for
the `*' or `.AND.' operators.
_See also_:

File: gfortran.info, Node: MAX, Next: MAXEXPONENT, Prev: MATMUL, Up: Intrinsic Procedures
9.189 `MAX' -- Maximum value of an argument list
================================================
_Description_:
Returns the argument with the largest (most positive) value.
_Standard_:
Fortran 77 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = MAX(A1, A2 [, A3 [, ...]])'
_Arguments_:
A1 The type shall be `INTEGER' or `REAL'.
A2, A3, An expression of the same type and kind as A1.
... (As a GNU extension, arguments of different
kinds are permitted.)
_Return value_:
The return value corresponds to the maximum value among the
arguments, and has the same type and kind as the first argument.
_Specific names_:
Name Argument Return type Standard
`MAX0(A1)' `INTEGER(4) `INTEGER(4)' Fortran 77 and
A1' later
`AMAX0(A1)' `INTEGER(4) `REAL(MAX(X))'Fortran 77 and
A1' later
`MAX1(A1)' `REAL A1' `INT(MAX(X))' Fortran 77 and
later
`AMAX1(A1)' `REAL(4) A1' `REAL(4)' Fortran 77 and
later
`DMAX1(A1)' `REAL(8) A1' `REAL(8)' Fortran 77 and
later
_See also_:
*note MAXLOC:: *note MAXVAL::, *note MIN::

File: gfortran.info, Node: MAXEXPONENT, Next: MAXLOC, Prev: MAX, Up: Intrinsic Procedures
9.190 `MAXEXPONENT' -- Maximum exponent of a real kind
======================================================
_Description_:
`MAXEXPONENT(X)' returns the maximum exponent in the model of the
type of `X'.
_Standard_:
Fortran 95 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = MAXEXPONENT(X)'
_Arguments_:
X Shall be of type `REAL'.
_Return value_:
The return value is of type `INTEGER' and of the default integer
kind.
_Example_:
program exponents
real(kind=4) :: x
real(kind=8) :: y
print *, minexponent(x), maxexponent(x)
print *, minexponent(y), maxexponent(y)
end program exponents

File: gfortran.info, Node: MAXLOC, Next: MAXVAL, Prev: MAXEXPONENT, Up: Intrinsic Procedures
9.191 `MAXLOC' -- Location of the maximum value within an array
===============================================================
_Description_:
Determines the location of the element in the array with the
maximum value, or, if the DIM argument is supplied, determines the
locations of the maximum element along each row of the array in the
DIM direction. If MASK is present, only the elements for which
MASK is `.TRUE.' are considered. If more than one element in the
array has the maximum value, the location returned is that of the
first such element in array element order if the BACK is not
present, or is false; if BACK is true, the location returned is
that of the last such element. If the array has zero size, or all
of the elements of MASK are `.FALSE.', then the result is an array
of zeroes. Similarly, if DIM is supplied and all of the elements
of MASK along a given row are zero, the result value for that row
is zero.
_Standard_:
Fortran 95 and later; ARRAY of `CHARACTER' and the KIND argument
are available in Fortran 2003 and later. The BACK argument is
available in Fortran 2008 and later.
_Class_:
Transformational function
_Syntax_:
`RESULT = MAXLOC(ARRAY, DIM [, MASK] [,KIND] [,BACK])'
`RESULT = MAXLOC(ARRAY [, MASK] [,KIND] [,BACK])'
_Arguments_:
ARRAY Shall be an array of type `INTEGER' or `REAL'.
DIM (Optional) Shall be a scalar of type
`INTEGER', with a value between one and the
rank of ARRAY, inclusive. It may not be an
optional dummy argument.
MASK Shall be an array of type `LOGICAL', and
conformable with ARRAY.
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
BACK (Optional) A scalar of type `LOGICAL'.
_Return value_:
If DIM is absent, the result is a rank-one array with a length
equal to the rank of ARRAY. If DIM is present, the result is an
array with a rank one less than the rank of ARRAY, and a size
corresponding to the size of ARRAY with the DIM dimension removed.
If DIM is present and ARRAY has a rank of one, the result is a
scalar. If the optional argument KIND is present, the result is
an integer of kind KIND, otherwise it is of default kind.
_See also_:
*note FINDLOC::, *note MAX::, *note MAXVAL::

File: gfortran.info, Node: MAXVAL, Next: MCLOCK, Prev: MAXLOC, Up: Intrinsic Procedures
9.192 `MAXVAL' -- Maximum value of an array
===========================================
_Description_:
Determines the maximum value of the elements in an array value,
or, if the DIM argument is supplied, determines the maximum value
along each row of the array in the DIM direction. If MASK is
present, only the elements for which MASK is `.TRUE.' are
considered. If the array has zero size, or all of the elements of
MASK are `.FALSE.', then the result is `-HUGE(ARRAY)' if ARRAY is
numeric, or a string of nulls if ARRAY is of character type.
_Standard_:
Fortran 95 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = MAXVAL(ARRAY, DIM [, MASK])'
`RESULT = MAXVAL(ARRAY [, MASK])'
_Arguments_:
ARRAY Shall be an array of type `INTEGER' or `REAL'.
DIM (Optional) Shall be a scalar of type
`INTEGER', with a value between one and the
rank of ARRAY, inclusive. It may not be an
optional dummy argument.
MASK Shall be an array of type `LOGICAL', and
conformable with ARRAY.
_Return value_:
If DIM is absent, or if ARRAY has a rank of one, the result is a
scalar. If DIM is present, the result is an array with a rank one
less than the rank of ARRAY, and a size corresponding to the size
of ARRAY with the DIM dimension removed. In all cases, the result
is of the same type and kind as ARRAY.
_See also_:
*note MAX::, *note MAXLOC::

File: gfortran.info, Node: MCLOCK, Next: MCLOCK8, Prev: MAXVAL, Up: Intrinsic Procedures
9.193 `MCLOCK' -- Time function
===============================
_Description_:
Returns the number of clock ticks since the start of the process,
based on the function `clock(3)' in the C standard library.
This intrinsic is not fully portable, such as to systems with
32-bit `INTEGER' types but supporting times wider than 32 bits.
Therefore, the values returned by this intrinsic might be, or
become, negative, or numerically less than previous values, during
a single run of the compiled program.
_Standard_:
GNU extension
_Class_:
Function
_Syntax_:
`RESULT = MCLOCK()'
_Return value_:
The return value is a scalar of type `INTEGER(4)', equal to the
number of clock ticks since the start of the process, or `-1' if
the system does not support `clock(3)'.
_See also_:
*note CTIME::, *note GMTIME::, *note LTIME::, *note MCLOCK::,
*note TIME::

File: gfortran.info, Node: MCLOCK8, Next: MERGE, Prev: MCLOCK, Up: Intrinsic Procedures
9.194 `MCLOCK8' -- Time function (64-bit)
=========================================
_Description_:
Returns the number of clock ticks since the start of the process,
based on the function `clock(3)' in the C standard library.
_Warning:_ this intrinsic does not increase the range of the timing
values over that returned by `clock(3)'. On a system with a 32-bit
`clock(3)', `MCLOCK8' will return a 32-bit value, even though it
is converted to a 64-bit `INTEGER(8)' value. That means overflows
of the 32-bit value can still occur. Therefore, the values
returned by this intrinsic might be or become negative or
numerically less than previous values during a single run of the
compiled program.
_Standard_:
GNU extension
_Class_:
Function
_Syntax_:
`RESULT = MCLOCK8()'
_Return value_:
The return value is a scalar of type `INTEGER(8)', equal to the
number of clock ticks since the start of the process, or `-1' if
the system does not support `clock(3)'.
_See also_:
*note CTIME::, *note GMTIME::, *note LTIME::, *note MCLOCK::,
*note TIME8::

File: gfortran.info, Node: MERGE, Next: MERGE_BITS, Prev: MCLOCK8, Up: Intrinsic Procedures
9.195 `MERGE' -- Merge variables
================================
_Description_:
Select values from two arrays according to a logical mask. The
result is equal to TSOURCE if MASK is `.TRUE.', or equal to
FSOURCE if it is `.FALSE.'.
_Standard_:
Fortran 95 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = MERGE(TSOURCE, FSOURCE, MASK)'
_Arguments_:
TSOURCE May be of any type.
FSOURCE Shall be of the same type and type parameters
as TSOURCE.
MASK Shall be of type `LOGICAL'.
_Return value_:
The result is of the same type and type parameters as TSOURCE.

File: gfortran.info, Node: MERGE_BITS, Next: MIN, Prev: MERGE, Up: Intrinsic Procedures
9.196 `MERGE_BITS' -- Merge of bits under mask
==============================================
_Description_:
`MERGE_BITS(I, J, MASK)' merges the bits of I and J as determined
by the mask. The i-th bit of the result is equal to the i-th bit
of I if the i-th bit of MASK is 1; it is equal to the i-th bit of
J otherwise.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = MERGE_BITS(I, J, MASK)'
_Arguments_:
I Shall be of type `INTEGER' or a
boz-literal-constant.
J Shall be of type `INTEGER' with the same kind
type parameter as I or a boz-literal-constant.
I and J shall not both be
boz-literal-constants.
MASK Shall be of type `INTEGER' or a
boz-literal-constant and of the same kind as I.
_Return value_:
The result is of the same type and kind as I.

File: gfortran.info, Node: MIN, Next: MINEXPONENT, Prev: MERGE_BITS, Up: Intrinsic Procedures
9.197 `MIN' -- Minimum value of an argument list
================================================
_Description_:
Returns the argument with the smallest (most negative) value.
_Standard_:
Fortran 77 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = MIN(A1, A2 [, A3, ...])'
_Arguments_:
A1 The type shall be `INTEGER' or `REAL'.
A2, A3, An expression of the same type and kind as A1.
... (As a GNU extension, arguments of different
kinds are permitted.)
_Return value_:
The return value corresponds to the maximum value among the
arguments, and has the same type and kind as the first argument.
_Specific names_:
Name Argument Return type Standard
`MIN0(A1)' `INTEGER(4) `INTEGER(4)' Fortran 77 and
A1' later
`AMIN0(A1)' `INTEGER(4) `REAL(4)' Fortran 77 and
A1' later
`MIN1(A1)' `REAL A1' `INTEGER(4)' Fortran 77 and
later
`AMIN1(A1)' `REAL(4) A1' `REAL(4)' Fortran 77 and
later
`DMIN1(A1)' `REAL(8) A1' `REAL(8)' Fortran 77 and
later
_See also_:
*note MAX::, *note MINLOC::, *note MINVAL::

File: gfortran.info, Node: MINEXPONENT, Next: MINLOC, Prev: MIN, Up: Intrinsic Procedures
9.198 `MINEXPONENT' -- Minimum exponent of a real kind
======================================================
_Description_:
`MINEXPONENT(X)' returns the minimum exponent in the model of the
type of `X'.
_Standard_:
Fortran 95 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = MINEXPONENT(X)'
_Arguments_:
X Shall be of type `REAL'.
_Return value_:
The return value is of type `INTEGER' and of the default integer
kind.
_Example_:
See `MAXEXPONENT' for an example.

File: gfortran.info, Node: MINLOC, Next: MINVAL, Prev: MINEXPONENT, Up: Intrinsic Procedures
9.199 `MINLOC' -- Location of the minimum value within an array
===============================================================
_Description_:
Determines the location of the element in the array with the
minimum value, or, if the DIM argument is supplied, determines the
locations of the minimum element along each row of the array in the
DIM direction. If MASK is present, only the elements for which
MASK is `.TRUE.' are considered. If more than one element in the
array has the minimum value, the location returned is that of the
first such element in array element order if the BACK is not
present, or is false; if BACK is true, the location returned is
that of the last such element. If the array has zero size, or all
of the elements of MASK are `.FALSE.', then the result is an array
of zeroes. Similarly, if DIM is supplied and all of the elements
of MASK along a given row are zero, the result value for that row
is zero.
_Standard_:
Fortran 95 and later; ARRAY of `CHARACTER' and the KIND argument
are available in Fortran 2003 and later. The BACK argument is
available in Fortran 2008 and later.
_Class_:
Transformational function
_Syntax_:
`RESULT = MINLOC(ARRAY, DIM [, MASK] [,KIND] [,BACK])'
`RESULT = MINLOC(ARRAY [, MASK], [,KIND] [,BACK])'
_Arguments_:
ARRAY Shall be an array of type `INTEGER', `REAL' or
`CHARACTER'.
DIM (Optional) Shall be a scalar of type
`INTEGER', with a value between one and the
rank of ARRAY, inclusive. It may not be an
optional dummy argument.
MASK Shall be an array of type `LOGICAL', and
conformable with ARRAY.
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
BACK (Optional) A scalar of type `LOGICAL'.
_Return value_:
If DIM is absent, the result is a rank-one array with a length
equal to the rank of ARRAY. If DIM is present, the result is an
array with a rank one less than the rank of ARRAY, and a size
corresponding to the size of ARRAY with the DIM dimension removed.
If DIM is present and ARRAY has a rank of one, the result is a
scalar. If the optional argument KIND is present, the result is
an integer of kind KIND, otherwise it is of default kind.
_See also_:
*note FINDLOC::, *note MIN::, *note MINVAL::

File: gfortran.info, Node: MINVAL, Next: MOD, Prev: MINLOC, Up: Intrinsic Procedures
9.200 `MINVAL' -- Minimum value of an array
===========================================
_Description_:
Determines the minimum value of the elements in an array value,
or, if the DIM argument is supplied, determines the minimum value
along each row of the array in the DIM direction. If MASK is
present, only the elements for which MASK is `.TRUE.' are
considered. If the array has zero size, or all of the elements of
MASK are `.FALSE.', then the result is `HUGE(ARRAY)' if ARRAY is
numeric, or a string of `CHAR(255)' characters if ARRAY is of
character type.
_Standard_:
Fortran 95 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = MINVAL(ARRAY, DIM [, MASK])'
`RESULT = MINVAL(ARRAY [, MASK])'
_Arguments_:
ARRAY Shall be an array of type `INTEGER' or `REAL'.
DIM (Optional) Shall be a scalar of type
`INTEGER', with a value between one and the
rank of ARRAY, inclusive. It may not be an
optional dummy argument.
MASK Shall be an array of type `LOGICAL', and
conformable with ARRAY.
_Return value_:
If DIM is absent, or if ARRAY has a rank of one, the result is a
scalar. If DIM is present, the result is an array with a rank one
less than the rank of ARRAY, and a size corresponding to the size
of ARRAY with the DIM dimension removed. In all cases, the result
is of the same type and kind as ARRAY.
_See also_:
*note MIN::, *note MINLOC::

File: gfortran.info, Node: MOD, Next: MODULO, Prev: MINVAL, Up: Intrinsic Procedures
9.201 `MOD' -- Remainder function
=================================
_Description_:
`MOD(A,P)' computes the remainder of the division of A by P.
_Standard_:
Fortran 77 and later, has overloads that are GNU extensions
_Class_:
Elemental function
_Syntax_:
`RESULT = MOD(A, P)'
_Arguments_:
A Shall be a scalar of type `INTEGER' or `REAL'.
P Shall be a scalar of the same type and kind as
A and not equal to zero.
_Return value_:
The return value is the result of `A - (INT(A/P) * P)'. The type
and kind of the return value is the same as that of the arguments.
The returned value has the same sign as A and a magnitude less
than the magnitude of P.
_Example_:
program test_mod
print *, mod(17,3)
print *, mod(17.5,5.5)
print *, mod(17.5d0,5.5)
print *, mod(17.5,5.5d0)
print *, mod(-17,3)
print *, mod(-17.5,5.5)
print *, mod(-17.5d0,5.5)
print *, mod(-17.5,5.5d0)
print *, mod(17,-3)
print *, mod(17.5,-5.5)
print *, mod(17.5d0,-5.5)
print *, mod(17.5,-5.5d0)
end program test_mod
_Specific names_:
Name Arguments Return type Standard
`MOD(A,P)' `INTEGER `INTEGER' Fortran 95 and
A,P' later
`AMOD(A,P)' `REAL(4) `REAL(4)' Fortran 95 and
A,P' later
`DMOD(A,P)' `REAL(8) `REAL(8)' Fortran 95 and
A,P' later
`BMOD(A,P)' `INTEGER(1) `INTEGER(1)' GNU extension
A,P'
`IMOD(A,P)' `INTEGER(2) `INTEGER(2)' GNU extension
A,P'
`JMOD(A,P)' `INTEGER(4) `INTEGER(4)' GNU extension
A,P'
`KMOD(A,P)' `INTEGER(8) `INTEGER(8)' GNU extension
A,P'
_See also_:
*note MODULO::

File: gfortran.info, Node: MODULO, Next: MOVE_ALLOC, Prev: MOD, Up: Intrinsic Procedures
9.202 `MODULO' -- Modulo function
=================================
_Description_:
`MODULO(A,P)' computes the A modulo P.
_Standard_:
Fortran 95 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = MODULO(A, P)'
_Arguments_:
A Shall be a scalar of type `INTEGER' or `REAL'.
P Shall be a scalar of the same type and kind as
A. It shall not be zero.
_Return value_:
The type and kind of the result are those of the arguments.
If A and P are of type `INTEGER':
`MODULO(A,P)' has the value R such that `A=Q*P+R', where Q is
an integer and R is between 0 (inclusive) and P (exclusive).
If A and P are of type `REAL':
`MODULO(A,P)' has the value of `A - FLOOR (A / P) * P'.
The returned value has the same sign as P and a magnitude less than
the magnitude of P.
_Example_:
program test_modulo
print *, modulo(17,3)
print *, modulo(17.5,5.5)
print *, modulo(-17,3)
print *, modulo(-17.5,5.5)
print *, modulo(17,-3)
print *, modulo(17.5,-5.5)
end program
_See also_:
*note MOD::

File: gfortran.info, Node: MOVE_ALLOC, Next: MVBITS, Prev: MODULO, Up: Intrinsic Procedures
9.203 `MOVE_ALLOC' -- Move allocation from one object to another
================================================================
_Description_:
`MOVE_ALLOC(FROM, TO)' moves the allocation from FROM to TO. FROM
will become deallocated in the process.
_Standard_:
Fortran 2003 and later
_Class_:
Pure subroutine
_Syntax_:
`CALL MOVE_ALLOC(FROM, TO)'
_Arguments_:
FROM `ALLOCATABLE', `INTENT(INOUT)', may be of any
type and kind.
TO `ALLOCATABLE', `INTENT(OUT)', shall be of the
same type, kind and rank as FROM.
_Return value_:
None
_Example_:
program test_move_alloc
integer, allocatable :: a(:), b(:)
allocate(a(3))
a = [ 1, 2, 3 ]
call move_alloc(a, b)
print *, allocated(a), allocated(b)
print *, b
end program test_move_alloc

File: gfortran.info, Node: MVBITS, Next: NEAREST, Prev: MOVE_ALLOC, Up: Intrinsic Procedures
9.204 `MVBITS' -- Move bits from one integer to another
=======================================================
_Description_:
Moves LEN bits from positions FROMPOS through `FROMPOS+LEN-1' of
FROM to positions TOPOS through `TOPOS+LEN-1' of TO. The portion
of argument TO not affected by the movement of bits is unchanged.
The values of `FROMPOS+LEN-1' and `TOPOS+LEN-1' must be less than
`BIT_SIZE(FROM)'.
_Standard_:
Fortran 95 and later, has overloads that are GNU extensions
_Class_:
Elemental subroutine
_Syntax_:
`CALL MVBITS(FROM, FROMPOS, LEN, TO, TOPOS)'
_Arguments_:
FROM The type shall be `INTEGER'.
FROMPOS The type shall be `INTEGER'.
LEN The type shall be `INTEGER'.
TO The type shall be `INTEGER', of the same kind
as FROM.
TOPOS The type shall be `INTEGER'.
_Specific names_:
Name Argument Return type Standard
`MVBITS(A)' `INTEGER A' `INTEGER' Fortran 95 and
later
`BMVBITS(A)' `INTEGER(1) `INTEGER(1)' GNU extension
A'
`IMVBITS(A)' `INTEGER(2) `INTEGER(2)' GNU extension
A'
`JMVBITS(A)' `INTEGER(4) `INTEGER(4)' GNU extension
A'
`KMVBITS(A)' `INTEGER(8) `INTEGER(8)' GNU extension
A'
_See also_:
*note IBCLR::, *note IBSET::, *note IBITS::, *note IAND::, *note
IOR::, *note IEOR::

File: gfortran.info, Node: NEAREST, Next: NEW_LINE, Prev: MVBITS, Up: Intrinsic Procedures
9.205 `NEAREST' -- Nearest representable number
===============================================
_Description_:
`NEAREST(X, S)' returns the processor-representable number nearest
to `X' in the direction indicated by the sign of `S'.
_Standard_:
Fortran 95 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = NEAREST(X, S)'
_Arguments_:
X Shall be of type `REAL'.
S Shall be of type `REAL' and not equal to zero.
_Return value_:
The return value is of the same type as `X'. If `S' is positive,
`NEAREST' returns the processor-representable number greater than
`X' and nearest to it. If `S' is negative, `NEAREST' returns the
processor-representable number smaller than `X' and nearest to it.
_Example_:
program test_nearest
real :: x, y
x = nearest(42.0, 1.0)
y = nearest(42.0, -1.0)
write (*,"(3(G20.15))") x, y, x - y
end program test_nearest

File: gfortran.info, Node: NEW_LINE, Next: NINT, Prev: NEAREST, Up: Intrinsic Procedures
9.206 `NEW_LINE' -- New line character
======================================
_Description_:
`NEW_LINE(C)' returns the new-line character.
_Standard_:
Fortran 2003 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = NEW_LINE(C)'
_Arguments_:
C The argument shall be a scalar or array of the
type `CHARACTER'.
_Return value_:
Returns a CHARACTER scalar of length one with the new-line
character of the same kind as parameter C.
_Example_:
program newline
implicit none
write(*,'(A)') 'This is record 1.'//NEW_LINE('A')//'This is record 2.'
end program newline

File: gfortran.info, Node: NINT, Next: NORM2, Prev: NEW_LINE, Up: Intrinsic Procedures
9.207 `NINT' -- Nearest whole number
====================================
_Description_:
`NINT(A)' rounds its argument to the nearest whole number.
_Standard_:
Fortran 77 and later, with KIND argument Fortran 90 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = NINT(A [, KIND])'
_Arguments_:
A The type of the argument shall be `REAL'.
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
_Return value_:
Returns A with the fractional portion of its magnitude eliminated
by rounding to the nearest whole number and with its sign
preserved, converted to an `INTEGER' of the default kind.
_Example_:
program test_nint
real(4) x4
real(8) x8
x4 = 1.234E0_4
x8 = 4.321_8
print *, nint(x4), idnint(x8)
end program test_nint
_Specific names_:
Name Argument Return Type Standard
`NINT(A)' `REAL(4) A' `INTEGER' Fortran 95 and
later
`IDNINT(A)' `REAL(8) A' `INTEGER' Fortran 95 and
later
_See also_:
*note CEILING::, *note FLOOR::

File: gfortran.info, Node: NORM2, Next: NOT, Prev: NINT, Up: Intrinsic Procedures
9.208 `NORM2' -- Euclidean vector norms
=======================================
_Description_:
Calculates the Euclidean vector norm (L_2 norm) of of ARRAY along
dimension DIM.
_Standard_:
Fortran 2008 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = NORM2(ARRAY[, DIM])'
_Arguments_:
ARRAY Shall be an array of type `REAL'
DIM (Optional) shall be a scalar of type `INTEGER'
with a value in the range from 1 to n, where n
equals the rank of ARRAY.
_Return value_:
The result is of the same type as ARRAY.
If DIM is absent, a scalar with the square root of the sum of all
elements in ARRAY squared is returned. Otherwise, an array of
rank n-1, where n equals the rank of ARRAY, and a shape similar to
that of ARRAY with dimension DIM dropped is returned.
_Example_:
PROGRAM test_sum
REAL :: x(5) = [ real :: 1, 2, 3, 4, 5 ]
print *, NORM2(x) ! = sqrt(55.) ~ 7.416
END PROGRAM

File: gfortran.info, Node: NOT, Next: NULL, Prev: NORM2, Up: Intrinsic Procedures
9.209 `NOT' -- Logical negation
===============================
_Description_:
`NOT' returns the bitwise Boolean inverse of I.
_Standard_:
Fortran 95 and later, has overloads that are GNU extensions
_Class_:
Elemental function
_Syntax_:
`RESULT = NOT(I)'
_Arguments_:
I The type shall be `INTEGER'.
_Return value_:
The return type is `INTEGER', of the same kind as the argument.
_Specific names_:
Name Argument Return type Standard
`NOT(A)' `INTEGER A' `INTEGER' Fortran 95 and
later
`BNOT(A)' `INTEGER(1) `INTEGER(1)' GNU extension
A'
`INOT(A)' `INTEGER(2) `INTEGER(2)' GNU extension
A'
`JNOT(A)' `INTEGER(4) `INTEGER(4)' GNU extension
A'
`KNOT(A)' `INTEGER(8) `INTEGER(8)' GNU extension
A'
_See also_:
*note IAND::, *note IEOR::, *note IOR::, *note IBITS::, *note
IBSET::, *note IBCLR::

File: gfortran.info, Node: NULL, Next: NUM_IMAGES, Prev: NOT, Up: Intrinsic Procedures
9.210 `NULL' -- Function that returns an disassociated pointer
==============================================================
_Description_:
Returns a disassociated pointer.
If MOLD is present, a disassociated pointer of the same type is
returned, otherwise the type is determined by context.
In Fortran 95, MOLD is optional. Please note that Fortran 2003
includes cases where it is required.
_Standard_:
Fortran 95 and later
_Class_:
Transformational function
_Syntax_:
`PTR => NULL([MOLD])'
_Arguments_:
MOLD (Optional) shall be a pointer of any
association status and of any type.
_Return value_:
A disassociated pointer.
_Example_:
REAL, POINTER, DIMENSION(:) :: VEC => NULL ()
_See also_:
*note ASSOCIATED::

File: gfortran.info, Node: NUM_IMAGES, Next: OR, Prev: NULL, Up: Intrinsic Procedures
9.211 `NUM_IMAGES' -- Function that returns the number of images
================================================================
_Description_:
Returns the number of images.
_Standard_:
Fortran 2008 and later. With DISTANCE or FAILED argument,
Technical Specification (TS) 18508 or later
_Class_:
Transformational function
_Syntax_:
`RESULT = NUM_IMAGES(DISTANCE, FAILED)'
_Arguments_:
DISTANCE (optional, intent(in)) Nonnegative scalar
integer
FAILED (optional, intent(in)) Scalar logical
expression
_Return value_:
Scalar default-kind integer. If DISTANCE is not present or has
value 0, the number of images in the current team is returned. For
values smaller or equal distance to the initial team, it returns
the number of images index on the ancestor team which has a
distance of DISTANCE from the invoking team. If DISTANCE is larger
than the distance to the initial team, the number of images of the
initial team is returned. If FAILED is not present the total
number of images is returned; if it has the value `.TRUE.', the
number of failed images is returned, otherwise, the number of
images which do have not the failed status.
_Example_:
INTEGER :: value[*]
INTEGER :: i
value = THIS_IMAGE()
SYNC ALL
IF (THIS_IMAGE() == 1) THEN
DO i = 1, NUM_IMAGES()
WRITE(*,'(2(a,i0))') 'value[', i, '] is ', value[i]
END DO
END IF
_See also_:
*note THIS_IMAGE::, *note IMAGE_INDEX::

File: gfortran.info, Node: OR, Next: PACK, Prev: NUM_IMAGES, Up: Intrinsic Procedures
9.212 `OR' -- Bitwise logical OR
================================
_Description_:
Bitwise logical `OR'.
This intrinsic routine is provided for backwards compatibility with
GNU Fortran 77. For integer arguments, programmers should consider
the use of the *note IOR:: intrinsic defined by the Fortran
standard.
_Standard_:
GNU extension
_Class_:
Function
_Syntax_:
`RESULT = OR(I, J)'
_Arguments_:
I The type shall be either a scalar `INTEGER'
type or a scalar `LOGICAL' type or a
boz-literal-constant.
J The type shall be the same as the type of I or
a boz-literal-constant. I and J shall not both
be boz-literal-constants. If either I and J
is a boz-literal-constant, then the other
argument must be a scalar `INTEGER'.
_Return value_:
The return type is either a scalar `INTEGER' or a scalar
`LOGICAL'. If the kind type parameters differ, then the smaller
kind type is implicitly converted to larger kind, and the return
has the larger kind. A boz-literal-constant is converted to an
`INTEGER' with the kind type parameter of the other argument as-if
a call to *note INT:: occurred.
_Example_:
PROGRAM test_or
LOGICAL :: T = .TRUE., F = .FALSE.
INTEGER :: a, b
DATA a / Z'F' /, b / Z'3' /
WRITE (*,*) OR(T, T), OR(T, F), OR(F, T), OR(F, F)
WRITE (*,*) OR(a, b)
END PROGRAM
_See also_:
Fortran 95 elemental function: *note IOR::

File: gfortran.info, Node: PACK, Next: PARITY, Prev: OR, Up: Intrinsic Procedures
9.213 `PACK' -- Pack an array into an array of rank one
=======================================================
_Description_:
Stores the elements of ARRAY in an array of rank one.
The beginning of the resulting array is made up of elements whose
MASK equals `TRUE'. Afterwards, positions are filled with elements
taken from VECTOR.
_Standard_:
Fortran 95 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = PACK(ARRAY, MASK[,VECTOR])'
_Arguments_:
ARRAY Shall be an array of any type.
MASK Shall be an array of type `LOGICAL' and of the
same size as ARRAY. Alternatively, it may be a
`LOGICAL' scalar.
VECTOR (Optional) shall be an array of the same type
as ARRAY and of rank one. If present, the
number of elements in VECTOR shall be equal to
or greater than the number of true elements in
MASK. If MASK is scalar, the number of
elements in VECTOR shall be equal to or
greater than the number of elements in ARRAY.
_Return value_:
The result is an array of rank one and the same type as that of
ARRAY. If VECTOR is present, the result size is that of VECTOR,
the number of `TRUE' values in MASK otherwise.
_Example_:
Gathering nonzero elements from an array:
PROGRAM test_pack_1
INTEGER :: m(6)
m = (/ 1, 0, 0, 0, 5, 0 /)
WRITE(*, FMT="(6(I0, ' '))") pack(m, m /= 0) ! "1 5"
END PROGRAM
Gathering nonzero elements from an array and appending elements
from VECTOR:
PROGRAM test_pack_2
INTEGER :: m(4)
m = (/ 1, 0, 0, 2 /)
WRITE(*, FMT="(4(I0, ' '))") pack(m, m /= 0, (/ 0, 0, 3, 4 /)) ! "1 2 3 4"
END PROGRAM
_See also_:
*note UNPACK::

File: gfortran.info, Node: PARITY, Next: PERROR, Prev: PACK, Up: Intrinsic Procedures
9.214 `PARITY' -- Reduction with exclusive OR
=============================================
_Description_:
Calculates the parity, i.e. the reduction using `.XOR.', of MASK
along dimension DIM.
_Standard_:
Fortran 2008 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = PARITY(MASK[, DIM])'
_Arguments_:
LOGICAL Shall be an array of type `LOGICAL'
DIM (Optional) shall be a scalar of type `INTEGER'
with a value in the range from 1 to n, where n
equals the rank of MASK.
_Return value_:
The result is of the same type as MASK.
If DIM is absent, a scalar with the parity of all elements in MASK
is returned, i.e. true if an odd number of elements is `.true.'
and false otherwise. If DIM is present, an array of rank n-1,
where n equals the rank of ARRAY, and a shape similar to that of
MASK with dimension DIM dropped is returned.
_Example_:
PROGRAM test_sum
LOGICAL :: x(2) = [ .true., .false. ]
print *, PARITY(x) ! prints "T" (true).
END PROGRAM

File: gfortran.info, Node: PERROR, Next: POPCNT, Prev: PARITY, Up: Intrinsic Procedures
9.215 `PERROR' -- Print system error message
============================================
_Description_:
Prints (on the C `stderr' stream) a newline-terminated error
message corresponding to the last system error. This is prefixed by
STRING, a colon and a space. See `perror(3)'.
_Standard_:
GNU extension
_Class_:
Subroutine
_Syntax_:
`CALL PERROR(STRING)'
_Arguments_:
STRING A scalar of type `CHARACTER' and of the
default kind.
_See also_:
*note IERRNO::

File: gfortran.info, Node: POPCNT, Next: POPPAR, Prev: PERROR, Up: Intrinsic Procedures
9.216 `POPCNT' -- Number of bits set
====================================
_Description_:
`POPCNT(I)' returns the number of bits set ('1' bits) in the binary
representation of `I'.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = POPCNT(I)'
_Arguments_:
I Shall be of type `INTEGER'.
_Return value_:
The return value is of type `INTEGER' and of the default integer
kind.
_See also_:
*note POPPAR::, *note LEADZ::, *note TRAILZ::
_Example_:
program test_population
print *, popcnt(127), poppar(127)
print *, popcnt(huge(0_4)), poppar(huge(0_4))
print *, popcnt(huge(0_8)), poppar(huge(0_8))
end program test_population

File: gfortran.info, Node: POPPAR, Next: PRECISION, Prev: POPCNT, Up: Intrinsic Procedures
9.217 `POPPAR' -- Parity of the number of bits set
==================================================
_Description_:
`POPPAR(I)' returns parity of the integer `I', i.e. the parity of
the number of bits set ('1' bits) in the binary representation of
`I'. It is equal to 0 if `I' has an even number of bits set, and 1
for an odd number of '1' bits.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = POPPAR(I)'
_Arguments_:
I Shall be of type `INTEGER'.
_Return value_:
The return value is of type `INTEGER' and of the default integer
kind.
_See also_:
*note POPCNT::, *note LEADZ::, *note TRAILZ::
_Example_:
program test_population
print *, popcnt(127), poppar(127)
print *, popcnt(huge(0_4)), poppar(huge(0_4))
print *, popcnt(huge(0_8)), poppar(huge(0_8))
end program test_population

File: gfortran.info, Node: PRECISION, Next: PRESENT, Prev: POPPAR, Up: Intrinsic Procedures
9.218 `PRECISION' -- Decimal precision of a real kind
=====================================================
_Description_:
`PRECISION(X)' returns the decimal precision in the model of the
type of `X'.
_Standard_:
Fortran 95 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = PRECISION(X)'
_Arguments_:
X Shall be of type `REAL' or `COMPLEX'.
_Return value_:
The return value is of type `INTEGER' and of the default integer
kind.
_See also_:
*note SELECTED_REAL_KIND::, *note RANGE::
_Example_:
program prec_and_range
real(kind=4) :: x(2)
complex(kind=8) :: y
print *, precision(x), range(x)
print *, precision(y), range(y)
end program prec_and_range

File: gfortran.info, Node: PRESENT, Next: PRODUCT, Prev: PRECISION, Up: Intrinsic Procedures
9.219 `PRESENT' -- Determine whether an optional dummy argument is specified
============================================================================
_Description_:
Determines whether an optional dummy argument is present.
_Standard_:
Fortran 95 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = PRESENT(A)'
_Arguments_:
A May be of any type and may be a pointer,
scalar or array value, or a dummy procedure.
It shall be the name of an optional dummy
argument accessible within the current
subroutine or function.
_Return value_:
Returns either `TRUE' if the optional argument A is present, or
`FALSE' otherwise.
_Example_:
PROGRAM test_present
WRITE(*,*) f(), f(42) ! "F T"
CONTAINS
LOGICAL FUNCTION f(x)
INTEGER, INTENT(IN), OPTIONAL :: x
f = PRESENT(x)
END FUNCTION
END PROGRAM

File: gfortran.info, Node: PRODUCT, Next: RADIX, Prev: PRESENT, Up: Intrinsic Procedures
9.220 `PRODUCT' -- Product of array elements
============================================
_Description_:
Multiplies the elements of ARRAY along dimension DIM if the
corresponding element in MASK is `TRUE'.
_Standard_:
Fortran 95 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = PRODUCT(ARRAY[, MASK])'
`RESULT = PRODUCT(ARRAY, DIM[, MASK])'
_Arguments_:
ARRAY Shall be an array of type `INTEGER', `REAL' or
`COMPLEX'.
DIM (Optional) shall be a scalar of type `INTEGER'
with a value in the range from 1 to n, where n
equals the rank of ARRAY.
MASK (Optional) shall be of type `LOGICAL' and
either be a scalar or an array of the same
shape as ARRAY.
_Return value_:
The result is of the same type as ARRAY.
If DIM is absent, a scalar with the product of all elements in
ARRAY is returned. Otherwise, an array of rank n-1, where n equals
the rank of ARRAY, and a shape similar to that of ARRAY with
dimension DIM dropped is returned.
_Example_:
PROGRAM test_product
INTEGER :: x(5) = (/ 1, 2, 3, 4 ,5 /)
print *, PRODUCT(x) ! all elements, product = 120
print *, PRODUCT(x, MASK=MOD(x, 2)==1) ! odd elements, product = 15
END PROGRAM
_See also_:
*note SUM::

File: gfortran.info, Node: RADIX, Next: RAN, Prev: PRODUCT, Up: Intrinsic Procedures
9.221 `RADIX' -- Base of a model number
=======================================
_Description_:
`RADIX(X)' returns the base of the model representing the entity X.
_Standard_:
Fortran 95 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = RADIX(X)'
_Arguments_:
X Shall be of type `INTEGER' or `REAL'
_Return value_:
The return value is a scalar of type `INTEGER' and of the default
integer kind.
_See also_:
*note SELECTED_REAL_KIND::
_Example_:
program test_radix
print *, "The radix for the default integer kind is", radix(0)
print *, "The radix for the default real kind is", radix(0.0)
end program test_radix

File: gfortran.info, Node: RAN, Next: RAND, Prev: RADIX, Up: Intrinsic Procedures
9.222 `RAN' -- Real pseudo-random number
========================================
_Description_:
For compatibility with HP FORTRAN 77/iX, the `RAN' intrinsic is
provided as an alias for `RAND'. See *note RAND:: for complete
documentation.
_Standard_:
GNU extension
_Class_:
Function
_See also_:
*note RAND::, *note RANDOM_NUMBER::

File: gfortran.info, Node: RAND, Next: RANDOM_INIT, Prev: RAN, Up: Intrinsic Procedures
9.223 `RAND' -- Real pseudo-random number
=========================================
_Description_:
`RAND(FLAG)' returns a pseudo-random number from a uniform
distribution between 0 and 1. If FLAG is 0, the next number in the
current sequence is returned; if FLAG is 1, the generator is
restarted by `CALL SRAND(0)'; if FLAG has any other value, it is
used as a new seed with `SRAND'.
This intrinsic routine is provided for backwards compatibility with
GNU Fortran 77. It implements a simple modulo generator as provided
by `g77'. For new code, one should consider the use of *note
RANDOM_NUMBER:: as it implements a superior algorithm.
_Standard_:
GNU extension
_Class_:
Function
_Syntax_:
`RESULT = RAND(I)'
_Arguments_:
I Shall be a scalar `INTEGER' of kind 4.
_Return value_:
The return value is of `REAL' type and the default kind.
_Example_:
program test_rand
integer,parameter :: seed = 86456
call srand(seed)
print *, rand(), rand(), rand(), rand()
print *, rand(seed), rand(), rand(), rand()
end program test_rand
_See also_:
*note SRAND::, *note RANDOM_NUMBER::

File: gfortran.info, Node: RANDOM_INIT, Next: RANDOM_NUMBER, Prev: RAND, Up: Intrinsic Procedures
9.224 `RANDOM_INIT' -- Initialize a pseudo-random number generator
==================================================================
_Description_:
Initializes the state of the pseudorandom number generator used by
`RANDOM_NUMBER'.
_Standard_:
Fortran 2018
_Class_:
Subroutine
_Syntax_:
`CALL RANDOM_INIT(REPEATABLE, IMAGE_DISTINCT)'
_Arguments_:
REPEATABLE Shall be a scalar with a `LOGICAL' type, and it
is `INTENT(IN)'. If it is `.true.', the seed is
set to a processor-dependent value that is the
same each time `RANDOM_INIT' is called from the
same image. The term "same image" means a single
instance of program execution. The sequence of
random numbers is different for repeated
execution of the program. If it is `.false.',
the seed is set to a processor-dependent value.
IMAGE_DISTINCTShall be a scalar with a `LOGICAL' type, and it
is `INTENT(IN)'. If it is `.true.', the seed is
set to a processor-dependent value that is
distinct from th seed set by a call to
`RANDOM_INIT' in another image. If it is
`.false.', the seed is set value that does depend
which image called `RANDOM_INIT'.
_Example_:
program test_random_seed
implicit none
real x(3), y(3)
call random_init(.true., .true.)
call random_number(x)
call random_init(.true., .true.)
call random_number(y)
! x and y are the same sequence
if (any(x /= y)) call abort
end program test_random_seed
_See also_:
*note RANDOM_NUMBER::, *note RANDOM_SEED::

File: gfortran.info, Node: RANDOM_NUMBER, Next: RANDOM_SEED, Prev: RANDOM_INIT, Up: Intrinsic Procedures
9.225 `RANDOM_NUMBER' -- Pseudo-random number
=============================================
_Description_:
Returns a single pseudorandom number or an array of pseudorandom
numbers from the uniform distribution over the range 0 \leq x < 1.
The runtime-library implements the xorshift1024* random number
generator (RNG). This generator has a period of 2^1024 - 1, and
when using multiple threads up to 2^512 threads can each generate
2^512 random numbers before any aliasing occurs.
Note that in a multi-threaded program (e.g. using OpenMP
directives), each thread will have its own random number state.
For details of the seeding procedure, see the documentation for
the `RANDOM_SEED' intrinsic.
_Standard_:
Fortran 95 and later
_Class_:
Subroutine
_Syntax_:
`RANDOM_NUMBER(HARVEST)'
_Arguments_:
HARVEST Shall be a scalar or an array of type `REAL'.
_Example_:
program test_random_number
REAL :: r(5,5)
CALL RANDOM_NUMBER(r)
end program
_See also_:
*note RANDOM_SEED::, *note RANDOM_INIT::

File: gfortran.info, Node: RANDOM_SEED, Next: RANGE, Prev: RANDOM_NUMBER, Up: Intrinsic Procedures
9.226 `RANDOM_SEED' -- Initialize a pseudo-random number sequence
=================================================================
_Description_:
Restarts or queries the state of the pseudorandom number generator
used by `RANDOM_NUMBER'.
If `RANDOM_SEED' is called without arguments, it is seeded with
random data retrieved from the operating system.
As an extension to the Fortran standard, the GFortran
`RANDOM_NUMBER' supports multiple threads. Each thread in a
multi-threaded program has its own seed. When `RANDOM_SEED' is
called either without arguments or with the PUT argument, the
given seed is copied into a master seed as well as the seed of the
current thread. When a new thread uses `RANDOM_NUMBER' for the
first time, the seed is copied from the master seed, and forwarded
N * 2^512 steps to guarantee that the random stream does not alias
any other stream in the system, where N is the number of threads
that have used `RANDOM_NUMBER' so far during the program execution.
_Standard_:
Fortran 95 and later
_Class_:
Subroutine
_Syntax_:
`CALL RANDOM_SEED([SIZE, PUT, GET])'
_Arguments_:
SIZE (Optional) Shall be a scalar and of type
default `INTEGER', with `INTENT(OUT)'. It
specifies the minimum size of the arrays used
with the PUT and GET arguments.
PUT (Optional) Shall be an array of type default
`INTEGER' and rank one. It is `INTENT(IN)' and
the size of the array must be larger than or
equal to the number returned by the SIZE
argument.
GET (Optional) Shall be an array of type default
`INTEGER' and rank one. It is `INTENT(OUT)'
and the size of the array must be larger than
or equal to the number returned by the SIZE
argument.
_Example_:
program test_random_seed
implicit none
integer, allocatable :: seed(:)
integer :: n
call random_seed(size = n)
allocate(seed(n))
call random_seed(get=seed)
write (*, *) seed
end program test_random_seed
_See also_:
*note RANDOM_NUMBER::, *note RANDOM_INIT::

File: gfortran.info, Node: RANGE, Next: RANK, Prev: RANDOM_SEED, Up: Intrinsic Procedures
9.227 `RANGE' -- Decimal exponent range
=======================================
_Description_:
`RANGE(X)' returns the decimal exponent range in the model of the
type of `X'.
_Standard_:
Fortran 95 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = RANGE(X)'
_Arguments_:
X Shall be of type `INTEGER', `REAL' or
`COMPLEX'.
_Return value_:
The return value is of type `INTEGER' and of the default integer
kind.
_See also_:
*note SELECTED_REAL_KIND::, *note PRECISION::
_Example_:
See `PRECISION' for an example.

File: gfortran.info, Node: RANK, Next: REAL, Prev: RANGE, Up: Intrinsic Procedures
9.228 `RANK' -- Rank of a data object
=====================================
_Description_:
`RANK(A)' returns the rank of a scalar or array data object.
_Standard_:
Technical Specification (TS) 29113
_Class_:
Inquiry function
_Syntax_:
`RESULT = RANK(A)'
_Arguments_:
A can be of any type
_Return value_:
The return value is of type `INTEGER' and of the default integer
kind. For arrays, their rank is returned; for scalars zero is
returned.
_Example_:
program test_rank
integer :: a
real, allocatable :: b(:,:)
print *, rank(a), rank(b) ! Prints: 0 2
end program test_rank

File: gfortran.info, Node: REAL, Next: RENAME, Prev: RANK, Up: Intrinsic Procedures
9.229 `REAL' -- Convert to real type
====================================
_Description_:
`REAL(A [, KIND])' converts its argument A to a real type. The
`REALPART' function is provided for compatibility with `g77', and
its use is strongly discouraged.
_Standard_:
Fortran 77 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = REAL(A [, KIND])'
`RESULT = REALPART(Z)'
_Arguments_:
A Shall be `INTEGER', `REAL', or `COMPLEX'.
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
_Return value_:
These functions return a `REAL' variable or array under the
following rules:
(A)
`REAL(A)' is converted to a default real type if A is an
integer or real variable.
(B)
`REAL(A)' is converted to a real type with the kind type
parameter of A if A is a complex variable.
(C)
`REAL(A, KIND)' is converted to a real type with kind type
parameter KIND if A is a complex, integer, or real variable.
_Example_:
program test_real
complex :: x = (1.0, 2.0)
print *, real(x), real(x,8), realpart(x)
end program test_real
_Specific names_:
Name Argument Return type Standard
`FLOAT(A)' `INTEGER(4)' `REAL(4)' Fortran 77 and
later
`DFLOAT(A)' `INTEGER(4)' `REAL(8)' GNU extension
`FLOATI(A)' `INTEGER(2)' `REAL(4)' GNU extension
`FLOATJ(A)' `INTEGER(4)' `REAL(4)' GNU extension
`FLOATK(A)' `INTEGER(8)' `REAL(4)' GNU extension
`SNGL(A)' `INTEGER(8)' `REAL(4)' Fortran 77 and
later
_See also_:
*note DBLE::

File: gfortran.info, Node: RENAME, Next: REPEAT, Prev: REAL, Up: Intrinsic Procedures
9.230 `RENAME' -- Rename a file
===============================
_Description_:
Renames a file from file PATH1 to PATH2. A null character
(`CHAR(0)') can be used to mark the end of the names in PATH1 and
PATH2; otherwise, trailing blanks in the file names are ignored.
If the STATUS argument is supplied, it contains 0 on success or a
nonzero error code upon return; see `rename(2)'.
This intrinsic is provided in both subroutine and function forms;
however, only one form can be used in any given program unit.
_Standard_:
GNU extension
_Class_:
Subroutine, function
_Syntax_:
`CALL RENAME(PATH1, PATH2 [, STATUS])'
`STATUS = RENAME(PATH1, PATH2)'
_Arguments_:
PATH1 Shall be of default `CHARACTER' type.
PATH2 Shall be of default `CHARACTER' type.
STATUS (Optional) Shall be of default `INTEGER' type.
_See also_:
*note LINK::

File: gfortran.info, Node: REPEAT, Next: RESHAPE, Prev: RENAME, Up: Intrinsic Procedures
9.231 `REPEAT' -- Repeated string concatenation
===============================================
_Description_:
Concatenates NCOPIES copies of a string.
_Standard_:
Fortran 95 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = REPEAT(STRING, NCOPIES)'
_Arguments_:
STRING Shall be scalar and of type `CHARACTER'.
NCOPIES Shall be scalar and of type `INTEGER'.
_Return value_:
A new scalar of type `CHARACTER' built up from NCOPIES copies of
STRING.
_Example_:
program test_repeat
write(*,*) repeat("x", 5) ! "xxxxx"
end program

File: gfortran.info, Node: RESHAPE, Next: RRSPACING, Prev: REPEAT, Up: Intrinsic Procedures
9.232 `RESHAPE' -- Function to reshape an array
===============================================
_Description_:
Reshapes SOURCE to correspond to SHAPE. If necessary, the new
array may be padded with elements from PAD or permuted as defined
by ORDER.
_Standard_:
Fortran 95 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = RESHAPE(SOURCE, SHAPE[, PAD, ORDER])'
_Arguments_:
SOURCE Shall be an array of any type.
SHAPE Shall be of type `INTEGER' and an array of
rank one. Its values must be positive or zero.
PAD (Optional) shall be an array of the same type
as SOURCE.
ORDER (Optional) shall be of type `INTEGER' and an
array of the same shape as SHAPE. Its values
shall be a permutation of the numbers from 1
to n, where n is the size of SHAPE. If ORDER
is absent, the natural ordering shall be
assumed.
_Return value_:
The result is an array of shape SHAPE with the same type as SOURCE.
_Example_:
PROGRAM test_reshape
INTEGER, DIMENSION(4) :: x
WRITE(*,*) SHAPE(x) ! prints "4"
WRITE(*,*) SHAPE(RESHAPE(x, (/2, 2/))) ! prints "2 2"
END PROGRAM
_See also_:
*note SHAPE::

File: gfortran.info, Node: RRSPACING, Next: RSHIFT, Prev: RESHAPE, Up: Intrinsic Procedures
9.233 `RRSPACING' -- Reciprocal of the relative spacing
=======================================================
_Description_:
`RRSPACING(X)' returns the reciprocal of the relative spacing of
model numbers near X.
_Standard_:
Fortran 95 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = RRSPACING(X)'
_Arguments_:
X Shall be of type `REAL'.
_Return value_:
The return value is of the same type and kind as X. The value
returned is equal to `ABS(FRACTION(X)) *
FLOAT(RADIX(X))**DIGITS(X)'.
_See also_:
*note SPACING::

File: gfortran.info, Node: RSHIFT, Next: SAME_TYPE_AS, Prev: RRSPACING, Up: Intrinsic Procedures
9.234 `RSHIFT' -- Right shift bits
==================================
_Description_:
`RSHIFT' returns a value corresponding to I with all of the bits
shifted right by SHIFT places. SHIFT shall be nonnegative and
less than or equal to `BIT_SIZE(I)', otherwise the result value is
undefined. Bits shifted out from the right end are lost. The fill
is arithmetic: the bits shifted in from the left end are equal to
the leftmost bit, which in two's complement representation is the
sign bit.
This function has been superseded by the `SHIFTA' intrinsic, which
is standard in Fortran 2008 and later.
_Standard_:
GNU extension
_Class_:
Elemental function
_Syntax_:
`RESULT = RSHIFT(I, SHIFT)'
_Arguments_:
I The type shall be `INTEGER'.
SHIFT The type shall be `INTEGER'.
_Return value_:
The return value is of type `INTEGER' and of the same kind as I.
_See also_:
*note ISHFT::, *note ISHFTC::, *note LSHIFT::, *note SHIFTA::,
*note SHIFTR::, *note SHIFTL::

File: gfortran.info, Node: SAME_TYPE_AS, Next: SCALE, Prev: RSHIFT, Up: Intrinsic Procedures
9.235 `SAME_TYPE_AS' -- Query dynamic types for equality
=========================================================
_Description_:
Query dynamic types for equality.
_Standard_:
Fortran 2003 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = SAME_TYPE_AS(A, B)'
_Arguments_:
A Shall be an object of extensible declared type
or unlimited polymorphic.
B Shall be an object of extensible declared type
or unlimited polymorphic.
_Return value_:
The return value is a scalar of type default logical. It is true
if and only if the dynamic type of A is the same as the dynamic
type of B.
_See also_:
*note EXTENDS_TYPE_OF::

File: gfortran.info, Node: SCALE, Next: SCAN, Prev: SAME_TYPE_AS, Up: Intrinsic Procedures
9.236 `SCALE' -- Scale a real value
===================================
_Description_:
`SCALE(X,I)' returns `X * RADIX(X)**I'.
_Standard_:
Fortran 95 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = SCALE(X, I)'
_Arguments_:
X The type of the argument shall be a `REAL'.
I The type of the argument shall be a `INTEGER'.
_Return value_:
The return value is of the same type and kind as X. Its value is
`X * RADIX(X)**I'.
_Example_:
program test_scale
real :: x = 178.1387e-4
integer :: i = 5
print *, scale(x,i), x*radix(x)**i
end program test_scale

File: gfortran.info, Node: SCAN, Next: SECNDS, Prev: SCALE, Up: Intrinsic Procedures
9.237 `SCAN' -- Scan a string for the presence of a set of characters
=====================================================================
_Description_:
Scans a STRING for any of the characters in a SET of characters.
If BACK is either absent or equals `FALSE', this function returns
the position of the leftmost character of STRING that is in SET.
If BACK equals `TRUE', the rightmost position is returned. If no
character of SET is found in STRING, the result is zero.
_Standard_:
Fortran 95 and later, with KIND argument Fortran 2003 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = SCAN(STRING, SET[, BACK [, KIND]])'
_Arguments_:
STRING Shall be of type `CHARACTER'.
SET Shall be of type `CHARACTER'.
BACK (Optional) shall be of type `LOGICAL'.
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
_Return value_:
The return value is of type `INTEGER' and of kind KIND. If KIND is
absent, the return value is of default integer kind.
_Example_:
PROGRAM test_scan
WRITE(*,*) SCAN("FORTRAN", "AO") ! 2, found 'O'
WRITE(*,*) SCAN("FORTRAN", "AO", .TRUE.) ! 6, found 'A'
WRITE(*,*) SCAN("FORTRAN", "C++") ! 0, found none
END PROGRAM
_See also_:
*note INDEX intrinsic::, *note VERIFY::

File: gfortran.info, Node: SECNDS, Next: SECOND, Prev: SCAN, Up: Intrinsic Procedures
9.238 `SECNDS' -- Time function
===============================
_Description_:
`SECNDS(X)' gets the time in seconds from the real-time system
clock. X is a reference time, also in seconds. If this is zero,
the time in seconds from midnight is returned. This function is
non-standard and its use is discouraged.
_Standard_:
GNU extension
_Class_:
Function
_Syntax_:
`RESULT = SECNDS (X)'
_Arguments_:
T Shall be of type `REAL(4)'.
X Shall be of type `REAL(4)'.
_Return value_:
None
_Example_:
program test_secnds
integer :: i
real(4) :: t1, t2
print *, secnds (0.0) ! seconds since midnight
t1 = secnds (0.0) ! reference time
do i = 1, 10000000 ! do something
end do
t2 = secnds (t1) ! elapsed time
print *, "Something took ", t2, " seconds."
end program test_secnds

File: gfortran.info, Node: SECOND, Next: SELECTED_CHAR_KIND, Prev: SECNDS, Up: Intrinsic Procedures
9.239 `SECOND' -- CPU time function
===================================
_Description_:
Returns a `REAL(4)' value representing the elapsed CPU time in
seconds. This provides the same functionality as the standard
`CPU_TIME' intrinsic, and is only included for backwards
compatibility.
This intrinsic is provided in both subroutine and function forms;
however, only one form can be used in any given program unit.
_Standard_:
GNU extension
_Class_:
Subroutine, function
_Syntax_:
`CALL SECOND(TIME)'
`TIME = SECOND()'
_Arguments_:
TIME Shall be of type `REAL(4)'.
_Return value_:
In either syntax, TIME is set to the process's current runtime in
seconds.
_See also_:
*note CPU_TIME::

File: gfortran.info, Node: SELECTED_CHAR_KIND, Next: SELECTED_INT_KIND, Prev: SECOND, Up: Intrinsic Procedures
9.240 `SELECTED_CHAR_KIND' -- Choose character kind
===================================================
_Description_:
`SELECTED_CHAR_KIND(NAME)' returns the kind value for the character
set named NAME, if a character set with such a name is supported,
or -1 otherwise. Currently, supported character sets include
"ASCII" and "DEFAULT", which are equivalent, and "ISO_10646"
(Universal Character Set, UCS-4) which is commonly known as
Unicode.
_Standard_:
Fortran 2003 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = SELECTED_CHAR_KIND(NAME)'
_Arguments_:
NAME Shall be a scalar and of the default character
type.
_Example_:
program character_kind
use iso_fortran_env
implicit none
integer, parameter :: ascii = selected_char_kind ("ascii")
integer, parameter :: ucs4 = selected_char_kind ('ISO_10646')
character(kind=ascii, len=26) :: alphabet
character(kind=ucs4, len=30) :: hello_world
alphabet = ascii_"abcdefghijklmnopqrstuvwxyz"
hello_world = ucs4_'Hello World and Ni Hao -- ' &
// char (int (z'4F60'), ucs4) &
// char (int (z'597D'), ucs4)
write (*,*) alphabet
open (output_unit, encoding='UTF-8')
write (*,*) trim (hello_world)
end program character_kind

File: gfortran.info, Node: SELECTED_INT_KIND, Next: SELECTED_REAL_KIND, Prev: SELECTED_CHAR_KIND, Up: Intrinsic Procedures
9.241 `SELECTED_INT_KIND' -- Choose integer kind
================================================
_Description_:
`SELECTED_INT_KIND(R)' return the kind value of the smallest
integer type that can represent all values ranging from -10^R
(exclusive) to 10^R (exclusive). If there is no integer kind that
accommodates this range, `SELECTED_INT_KIND' returns -1.
_Standard_:
Fortran 95 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = SELECTED_INT_KIND(R)'
_Arguments_:
R Shall be a scalar and of type `INTEGER'.
_Example_:
program large_integers
integer,parameter :: k5 = selected_int_kind(5)
integer,parameter :: k15 = selected_int_kind(15)
integer(kind=k5) :: i5
integer(kind=k15) :: i15
print *, huge(i5), huge(i15)
! The following inequalities are always true
print *, huge(i5) >= 10_k5**5-1
print *, huge(i15) >= 10_k15**15-1
end program large_integers

File: gfortran.info, Node: SELECTED_REAL_KIND, Next: SET_EXPONENT, Prev: SELECTED_INT_KIND, Up: Intrinsic Procedures
9.242 `SELECTED_REAL_KIND' -- Choose real kind
==============================================
_Description_:
`SELECTED_REAL_KIND(P,R)' returns the kind value of a real data
type with decimal precision of at least `P' digits, exponent range
of at least `R', and with a radix of `RADIX'.
_Standard_:
Fortran 95 and later, with `RADIX' Fortran 2008 or later
_Class_:
Transformational function
_Syntax_:
`RESULT = SELECTED_REAL_KIND([P, R, RADIX])'
_Arguments_:
P (Optional) shall be a scalar and of type
`INTEGER'.
R (Optional) shall be a scalar and of type
`INTEGER'.
RADIX (Optional) shall be a scalar and of type
`INTEGER'.
Before Fortran 2008, at least one of the arguments R or P shall be
present; since Fortran 2008, they are assumed to be zero if absent.
_Return value_:
`SELECTED_REAL_KIND' returns the value of the kind type parameter
of a real data type with decimal precision of at least `P' digits,
a decimal exponent range of at least `R', and with the requested
`RADIX'. If the `RADIX' parameter is absent, real kinds with any
radix can be returned. If more than one real data type meet the
criteria, the kind of the data type with the smallest decimal
precision is returned. If no real data type matches the criteria,
the result is
-1 if the processor does not support a real data type with a
precision greater than or equal to `P', but the `R' and
`RADIX' requirements can be fulfilled
-2 if the processor does not support a real type with an exponent
range greater than or equal to `R', but `P' and `RADIX' are
fulfillable
-3 if `RADIX' but not `P' and `R' requirements
are fulfillable
-4 if `RADIX' and either `P' or `R' requirements
are fulfillable
-5 if there is no real type with the given `RADIX'
_See also_:
*note PRECISION::, *note RANGE::, *note RADIX::
_Example_:
program real_kinds
integer,parameter :: p6 = selected_real_kind(6)
integer,parameter :: p10r100 = selected_real_kind(10,100)
integer,parameter :: r400 = selected_real_kind(r=400)
real(kind=p6) :: x
real(kind=p10r100) :: y
real(kind=r400) :: z
print *, precision(x), range(x)
print *, precision(y), range(y)
print *, precision(z), range(z)
end program real_kinds

File: gfortran.info, Node: SET_EXPONENT, Next: SHAPE, Prev: SELECTED_REAL_KIND, Up: Intrinsic Procedures
9.243 `SET_EXPONENT' -- Set the exponent of the model
=====================================================
_Description_:
`SET_EXPONENT(X, I)' returns the real number whose fractional part
is that that of X and whose exponent part is I.
_Standard_:
Fortran 95 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = SET_EXPONENT(X, I)'
_Arguments_:
X Shall be of type `REAL'.
I Shall be of type `INTEGER'.
_Return value_:
The return value is of the same type and kind as X. The real
number whose fractional part is that that of X and whose exponent
part if I is returned; it is `FRACTION(X) * RADIX(X)**I'.
_Example_:
PROGRAM test_setexp
REAL :: x = 178.1387e-4
INTEGER :: i = 17
PRINT *, SET_EXPONENT(x, i), FRACTION(x) * RADIX(x)**i
END PROGRAM

File: gfortran.info, Node: SHAPE, Next: SHIFTA, Prev: SET_EXPONENT, Up: Intrinsic Procedures
9.244 `SHAPE' -- Determine the shape of an array
================================================
_Description_:
Determines the shape of an array.
_Standard_:
Fortran 95 and later, with KIND argument Fortran 2003 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = SHAPE(SOURCE [, KIND])'
_Arguments_:
SOURCE Shall be an array or scalar of any type. If
SOURCE is a pointer it must be associated and
allocatable arrays must be allocated.
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
_Return value_:
An `INTEGER' array of rank one with as many elements as SOURCE has
dimensions. The elements of the resulting array correspond to the
extend of SOURCE along the respective dimensions. If SOURCE is a
scalar, the result is the rank one array of size zero. If KIND is
absent, the return value has the default integer kind otherwise
the specified kind.
_Example_:
PROGRAM test_shape
INTEGER, DIMENSION(-1:1, -1:2) :: A
WRITE(*,*) SHAPE(A) ! (/ 3, 4 /)
WRITE(*,*) SIZE(SHAPE(42)) ! (/ /)
END PROGRAM
_See also_:
*note RESHAPE::, *note SIZE::

File: gfortran.info, Node: SHIFTA, Next: SHIFTL, Prev: SHAPE, Up: Intrinsic Procedures
9.245 `SHIFTA' -- Right shift with fill
=======================================
_Description_:
`SHIFTA' returns a value corresponding to I with all of the bits
shifted right by SHIFT places. SHIFT that be nonnegative and less
than or equal to `BIT_SIZE(I)', otherwise the result value is
undefined. Bits shifted out from the right end are lost. The fill
is arithmetic: the bits shifted in from the left end are equal to
the leftmost bit, which in two's complement representation is the
sign bit.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = SHIFTA(I, SHIFT)'
_Arguments_:
I The type shall be `INTEGER'.
SHIFT The type shall be `INTEGER'.
_Return value_:
The return value is of type `INTEGER' and of the same kind as I.
_See also_:
*note SHIFTL::, *note SHIFTR::

File: gfortran.info, Node: SHIFTL, Next: SHIFTR, Prev: SHIFTA, Up: Intrinsic Procedures
9.246 `SHIFTL' -- Left shift
============================
_Description_:
`SHIFTL' returns a value corresponding to I with all of the bits
shifted left by SHIFT places. SHIFT shall be nonnegative and less
than or equal to `BIT_SIZE(I)', otherwise the result value is
undefined. Bits shifted out from the left end are lost, and bits
shifted in from the right end are set to 0.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = SHIFTL(I, SHIFT)'
_Arguments_:
I The type shall be `INTEGER'.
SHIFT The type shall be `INTEGER'.
_Return value_:
The return value is of type `INTEGER' and of the same kind as I.
_See also_:
*note SHIFTA::, *note SHIFTR::

File: gfortran.info, Node: SHIFTR, Next: SIGN, Prev: SHIFTL, Up: Intrinsic Procedures
9.247 `SHIFTR' -- Right shift
=============================
_Description_:
`SHIFTR' returns a value corresponding to I with all of the bits
shifted right by SHIFT places. SHIFT shall be nonnegative and
less than or equal to `BIT_SIZE(I)', otherwise the result value is
undefined. Bits shifted out from the right end are lost, and bits
shifted in from the left end are set to 0.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = SHIFTR(I, SHIFT)'
_Arguments_:
I The type shall be `INTEGER'.
SHIFT The type shall be `INTEGER'.
_Return value_:
The return value is of type `INTEGER' and of the same kind as I.
_See also_:
*note SHIFTA::, *note SHIFTL::

File: gfortran.info, Node: SIGN, Next: SIGNAL, Prev: SHIFTR, Up: Intrinsic Procedures
9.248 `SIGN' -- Sign copying function
=====================================
_Description_:
`SIGN(A,B)' returns the value of A with the sign of B.
_Standard_:
Fortran 77 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = SIGN(A, B)'
_Arguments_:
A Shall be of type `INTEGER' or `REAL'
B Shall be of the same type and kind as A
_Return value_:
The kind of the return value is that of A and B. If B\ge 0 then
the result is `ABS(A)', else it is `-ABS(A)'.
_Example_:
program test_sign
print *, sign(-12,1)
print *, sign(-12,0)
print *, sign(-12,-1)
print *, sign(-12.,1.)
print *, sign(-12.,0.)
print *, sign(-12.,-1.)
end program test_sign
_Specific names_:
Name Arguments Return type Standard
`SIGN(A,B)' `REAL(4) A, `REAL(4)' f77, gnu
B'
`ISIGN(A,B)' `INTEGER(4) `INTEGER(4)' f77, gnu
A, B'
`DSIGN(A,B)' `REAL(8) A, `REAL(8)' f77, gnu
B'

File: gfortran.info, Node: SIGNAL, Next: SIN, Prev: SIGN, Up: Intrinsic Procedures
9.249 `SIGNAL' -- Signal handling subroutine (or function)
==========================================================
_Description_:
`SIGNAL(NUMBER, HANDLER [, STATUS])' causes external subroutine
HANDLER to be executed with a single integer argument when signal
NUMBER occurs. If HANDLER is an integer, it can be used to turn
off handling of signal NUMBER or revert to its default action.
See `signal(2)'.
If `SIGNAL' is called as a subroutine and the STATUS argument is
supplied, it is set to the value returned by `signal(2)'.
_Standard_:
GNU extension
_Class_:
Subroutine, function
_Syntax_:
`CALL SIGNAL(NUMBER, HANDLER [, STATUS])'
`STATUS = SIGNAL(NUMBER, HANDLER)'
_Arguments_:
NUMBER Shall be a scalar integer, with `INTENT(IN)'
HANDLER Signal handler (`INTEGER FUNCTION' or
`SUBROUTINE') or dummy/global `INTEGER' scalar.
`INTEGER'. It is `INTENT(IN)'.
STATUS (Optional) STATUS shall be a scalar integer.
It has `INTENT(OUT)'.
_Return value_:
The `SIGNAL' function returns the value returned by `signal(2)'.
_Example_:
program test_signal
intrinsic signal
external handler_print
call signal (12, handler_print)
call signal (10, 1)
call sleep (30)
end program test_signal

File: gfortran.info, Node: SIN, Next: SIND, Prev: SIGNAL, Up: Intrinsic Procedures
9.250 `SIN' -- Sine function
============================
_Description_:
`SIN(X)' computes the sine of X.
_Standard_:
Fortran 77 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = SIN(X)'
_Arguments_:
X The type shall be `REAL' or `COMPLEX'.
_Return value_:
The return value has same type and kind as X.
_Example_:
program test_sin
real :: x = 0.0
x = sin(x)
end program test_sin
_Specific names_:
Name Argument Return type Standard
`SIN(X)' `REAL(4) X' `REAL(4)' f77, gnu
`DSIN(X)' `REAL(8) X' `REAL(8)' f95, gnu
`CSIN(X)' `COMPLEX(4) `COMPLEX(4)' f95, gnu
X'
`ZSIN(X)' `COMPLEX(8) `COMPLEX(8)' f95, gnu
X'
`CDSIN(X)' `COMPLEX(8) `COMPLEX(8)' f95, gnu
X'
_See also_:
Inverse function: *note ASIN:: Degrees function: *note SIND::

File: gfortran.info, Node: SIND, Next: SINH, Prev: SIN, Up: Intrinsic Procedures
9.251 `SIND' -- Sine function, degrees
======================================
_Description_:
`SIND(X)' computes the sine of X in degrees.
This function is for compatibility only and should be avoided in
favor of standard constructs wherever possible.
_Standard_:
GNU Extension, enabled with `-fdec-math'.
_Class_:
Elemental function
_Syntax_:
`RESULT = SIND(X)'
_Arguments_:
X The type shall be `REAL' or `COMPLEX'.
_Return value_:
The return value has same type and kind as X, and its value is in
degrees.
_Example_:
program test_sind
real :: x = 0.0
x = sind(x)
end program test_sind
_Specific names_:
Name Argument Return type Standard
`SIND(X)' `REAL(4) X' `REAL(4)' GNU Extension
`DSIND(X)' `REAL(8) X' `REAL(8)' GNU Extension
`CSIND(X)' `COMPLEX(4) `COMPLEX(4)' GNU Extension
X'
`ZSIND(X)' `COMPLEX(8) `COMPLEX(8)' GNU Extension
X'
`CDSIND(X)' `COMPLEX(8) `COMPLEX(8)' GNU Extension
X'
_See also_:
Inverse function: *note ASIND:: Radians function: *note SIN::

File: gfortran.info, Node: SINH, Next: SIZE, Prev: SIND, Up: Intrinsic Procedures
9.252 `SINH' -- Hyperbolic sine function
========================================
_Description_:
`SINH(X)' computes the hyperbolic sine of X.
_Standard_:
Fortran 95 and later, for a complex argument Fortran 2008 or later
_Class_:
Elemental function
_Syntax_:
`RESULT = SINH(X)'
_Arguments_:
X The type shall be `REAL' or `COMPLEX'.
_Return value_:
The return value has same type and kind as X.
_Example_:
program test_sinh
real(8) :: x = - 1.0_8
x = sinh(x)
end program test_sinh
_Specific names_:
Name Argument Return type Standard
`SINH(X)' `REAL(4) X' `REAL(4)' Fortran 95 and
later
`DSINH(X)' `REAL(8) X' `REAL(8)' Fortran 95 and
later
_See also_:
*note ASINH::

File: gfortran.info, Node: SIZE, Next: SIZEOF, Prev: SINH, Up: Intrinsic Procedures
9.253 `SIZE' -- Determine the size of an array
==============================================
_Description_:
Determine the extent of ARRAY along a specified dimension DIM, or
the total number of elements in ARRAY if DIM is absent.
_Standard_:
Fortran 95 and later, with KIND argument Fortran 2003 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = SIZE(ARRAY[, DIM [, KIND]])'
_Arguments_:
ARRAY Shall be an array of any type. If ARRAY is a
pointer it must be associated and allocatable
arrays must be allocated.
DIM (Optional) shall be a scalar of type `INTEGER'
and its value shall be in the range from 1 to
n, where n equals the rank of ARRAY.
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
_Return value_:
The return value is of type `INTEGER' and of kind KIND. If KIND is
absent, the return value is of default integer kind.
_Example_:
PROGRAM test_size
WRITE(*,*) SIZE((/ 1, 2 /)) ! 2
END PROGRAM
_See also_:
*note SHAPE::, *note RESHAPE::

File: gfortran.info, Node: SIZEOF, Next: SLEEP, Prev: SIZE, Up: Intrinsic Procedures
9.254 `SIZEOF' -- Size in bytes of an expression
================================================
_Description_:
`SIZEOF(X)' calculates the number of bytes of storage the
expression `X' occupies.
_Standard_:
GNU extension
_Class_:
Inquiry function
_Syntax_:
`N = SIZEOF(X)'
_Arguments_:
X The argument shall be of any type, rank or
shape.
_Return value_:
The return value is of type integer and of the system-dependent
kind C_SIZE_T (from the ISO_C_BINDING module). Its value is the
number of bytes occupied by the argument. If the argument has the
`POINTER' attribute, the number of bytes of the storage area
pointed to is returned. If the argument is of a derived type with
`POINTER' or `ALLOCATABLE' components, the return value does not
account for the sizes of the data pointed to by these components.
If the argument is polymorphic, the size according to the dynamic
type is returned. The argument may not be a procedure or procedure
pointer. Note that the code assumes for arrays that those are
contiguous; for contiguous arrays, it returns the storage or an
array element multiplied by the size of the array.
_Example_:
integer :: i
real :: r, s(5)
print *, (sizeof(s)/sizeof(r) == 5)
end
The example will print `.TRUE.' unless you are using a platform
where default `REAL' variables are unusually padded.
_See also_:
*note C_SIZEOF::, *note STORAGE_SIZE::

File: gfortran.info, Node: SLEEP, Next: SPACING, Prev: SIZEOF, Up: Intrinsic Procedures
9.255 `SLEEP' -- Sleep for the specified number of seconds
==========================================================
_Description_:
Calling this subroutine causes the process to pause for SECONDS
seconds.
_Standard_:
GNU extension
_Class_:
Subroutine
_Syntax_:
`CALL SLEEP(SECONDS)'
_Arguments_:
SECONDS The type shall be of default `INTEGER'.
_Example_:
program test_sleep
call sleep(5)
end

File: gfortran.info, Node: SPACING, Next: SPREAD, Prev: SLEEP, Up: Intrinsic Procedures
9.256 `SPACING' -- Smallest distance between two numbers of a given type
========================================================================
_Description_:
Determines the distance between the argument X and the nearest
adjacent number of the same type.
_Standard_:
Fortran 95 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = SPACING(X)'
_Arguments_:
X Shall be of type `REAL'.
_Return value_:
The result is of the same type as the input argument X.
_Example_:
PROGRAM test_spacing
INTEGER, PARAMETER :: SGL = SELECTED_REAL_KIND(p=6, r=37)
INTEGER, PARAMETER :: DBL = SELECTED_REAL_KIND(p=13, r=200)
WRITE(*,*) spacing(1.0_SGL) ! "1.1920929E-07" on i686
WRITE(*,*) spacing(1.0_DBL) ! "2.220446049250313E-016" on i686
END PROGRAM
_See also_:
*note RRSPACING::

File: gfortran.info, Node: SPREAD, Next: SQRT, Prev: SPACING, Up: Intrinsic Procedures
9.257 `SPREAD' -- Add a dimension to an array
=============================================
_Description_:
Replicates a SOURCE array NCOPIES times along a specified
dimension DIM.
_Standard_:
Fortran 95 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = SPREAD(SOURCE, DIM, NCOPIES)'
_Arguments_:
SOURCE Shall be a scalar or an array of any type and
a rank less than seven.
DIM Shall be a scalar of type `INTEGER' with a
value in the range from 1 to n+1, where n
equals the rank of SOURCE.
NCOPIES Shall be a scalar of type `INTEGER'.
_Return value_:
The result is an array of the same type as SOURCE and has rank n+1
where n equals the rank of SOURCE.
_Example_:
PROGRAM test_spread
INTEGER :: a = 1, b(2) = (/ 1, 2 /)
WRITE(*,*) SPREAD(A, 1, 2) ! "1 1"
WRITE(*,*) SPREAD(B, 1, 2) ! "1 1 2 2"
END PROGRAM
_See also_:
*note UNPACK::

File: gfortran.info, Node: SQRT, Next: SRAND, Prev: SPREAD, Up: Intrinsic Procedures
9.258 `SQRT' -- Square-root function
====================================
_Description_:
`SQRT(X)' computes the square root of X.
_Standard_:
Fortran 77 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = SQRT(X)'
_Arguments_:
X The type shall be `REAL' or `COMPLEX'.
_Return value_:
The return value is of type `REAL' or `COMPLEX'. The kind type
parameter is the same as X.
_Example_:
program test_sqrt
real(8) :: x = 2.0_8
complex :: z = (1.0, 2.0)
x = sqrt(x)
z = sqrt(z)
end program test_sqrt
_Specific names_:
Name Argument Return type Standard
`SQRT(X)' `REAL(4) X' `REAL(4)' Fortran 95 and
later
`DSQRT(X)' `REAL(8) X' `REAL(8)' Fortran 95 and
later
`CSQRT(X)' `COMPLEX(4) `COMPLEX(4)' Fortran 95 and
X' later
`ZSQRT(X)' `COMPLEX(8) `COMPLEX(8)' GNU extension
X'
`CDSQRT(X)' `COMPLEX(8) `COMPLEX(8)' GNU extension
X'

File: gfortran.info, Node: SRAND, Next: STAT, Prev: SQRT, Up: Intrinsic Procedures
9.259 `SRAND' -- Reinitialize the random number generator
=========================================================
_Description_:
`SRAND' reinitializes the pseudo-random number generator called by
`RAND' and `IRAND'. The new seed used by the generator is
specified by the required argument SEED.
_Standard_:
GNU extension
_Class_:
Subroutine
_Syntax_:
`CALL SRAND(SEED)'
_Arguments_:
SEED Shall be a scalar `INTEGER(kind=4)'.
_Return value_:
Does not return anything.
_Example_:
See `RAND' and `IRAND' for examples.
_Notes_:
The Fortran standard specifies the intrinsic subroutines
`RANDOM_SEED' to initialize the pseudo-random number generator and
`RANDOM_NUMBER' to generate pseudo-random numbers. These
subroutines should be used in new codes.
Please note that in GNU Fortran, these two sets of intrinsics
(`RAND', `IRAND' and `SRAND' on the one hand, `RANDOM_NUMBER' and
`RANDOM_SEED' on the other hand) access two independent
pseudo-random number generators.
_See also_:
*note RAND::, *note RANDOM_SEED::, *note RANDOM_NUMBER::

File: gfortran.info, Node: STAT, Next: STORAGE_SIZE, Prev: SRAND, Up: Intrinsic Procedures
9.260 `STAT' -- Get file status
===============================
_Description_:
This function returns information about a file. No permissions are
required on the file itself, but execute (search) permission is
required on all of the directories in path that lead to the file.
The elements that are obtained and stored in the array `VALUES':
`VALUES(1)'Device ID
`VALUES(2)'Inode number
`VALUES(3)'File mode
`VALUES(4)'Number of links
`VALUES(5)'Owner's uid
`VALUES(6)'Owner's gid
`VALUES(7)'ID of device containing directory entry for
file (0 if not available)
`VALUES(8)'File size (bytes)
`VALUES(9)'Last access time
`VALUES(10)'Last modification time
`VALUES(11)'Last file status change time
`VALUES(12)'Preferred I/O block size (-1 if not available)
`VALUES(13)'Number of blocks allocated (-1 if not
available)
Not all these elements are relevant on all systems. If an element
is not relevant, it is returned as 0.
This intrinsic is provided in both subroutine and function forms;
however, only one form can be used in any given program unit.
_Standard_:
GNU extension
_Class_:
Subroutine, function
_Syntax_:
`CALL STAT(NAME, VALUES [, STATUS])'
`STATUS = STAT(NAME, VALUES)'
_Arguments_:
NAME The type shall be `CHARACTER', of the default
kind and a valid path within the file system.
VALUES The type shall be `INTEGER(4), DIMENSION(13)'.
STATUS (Optional) status flag of type `INTEGER(4)'.
Returns 0 on success and a system specific
error code otherwise.
_Example_:
PROGRAM test_stat
INTEGER, DIMENSION(13) :: buff
INTEGER :: status
CALL STAT("/etc/passwd", buff, status)
IF (status == 0) THEN
WRITE (*, FMT="('Device ID:', T30, I19)") buff(1)
WRITE (*, FMT="('Inode number:', T30, I19)") buff(2)
WRITE (*, FMT="('File mode (octal):', T30, O19)") buff(3)
WRITE (*, FMT="('Number of links:', T30, I19)") buff(4)
WRITE (*, FMT="('Owner''s uid:', T30, I19)") buff(5)
WRITE (*, FMT="('Owner''s gid:', T30, I19)") buff(6)
WRITE (*, FMT="('Device where located:', T30, I19)") buff(7)
WRITE (*, FMT="('File size:', T30, I19)") buff(8)
WRITE (*, FMT="('Last access time:', T30, A19)") CTIME(buff(9))
WRITE (*, FMT="('Last modification time', T30, A19)") CTIME(buff(10))
WRITE (*, FMT="('Last status change time:', T30, A19)") CTIME(buff(11))
WRITE (*, FMT="('Preferred block size:', T30, I19)") buff(12)
WRITE (*, FMT="('No. of blocks allocated:', T30, I19)") buff(13)
END IF
END PROGRAM
_See also_:
To stat an open file: *note FSTAT::, to stat a link: *note LSTAT::

File: gfortran.info, Node: STORAGE_SIZE, Next: SUM, Prev: STAT, Up: Intrinsic Procedures
9.261 `STORAGE_SIZE' -- Storage size in bits
============================================
_Description_:
Returns the storage size of argument A in bits.
_Standard_:
Fortran 2008 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = STORAGE_SIZE(A [, KIND])'
_Arguments_:
A Shall be a scalar or array of any type.
KIND (Optional) shall be a scalar integer constant
expression.
_Return Value_:
The result is a scalar integer with the kind type parameter
specified by KIND (or default integer type if KIND is missing).
The result value is the size expressed in bits for an element of
an array that has the dynamic type and type parameters of A.
_See also_:
*note C_SIZEOF::, *note SIZEOF::

File: gfortran.info, Node: SUM, Next: SYMLNK, Prev: STORAGE_SIZE, Up: Intrinsic Procedures
9.262 `SUM' -- Sum of array elements
====================================
_Description_:
Adds the elements of ARRAY along dimension DIM if the
corresponding element in MASK is `TRUE'.
_Standard_:
Fortran 95 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = SUM(ARRAY[, MASK])'
`RESULT = SUM(ARRAY, DIM[, MASK])'
_Arguments_:
ARRAY Shall be an array of type `INTEGER', `REAL' or
`COMPLEX'.
DIM (Optional) shall be a scalar of type `INTEGER'
with a value in the range from 1 to n, where n
equals the rank of ARRAY.
MASK (Optional) shall be of type `LOGICAL' and
either be a scalar or an array of the same
shape as ARRAY.
_Return value_:
The result is of the same type as ARRAY.
If DIM is absent, a scalar with the sum of all elements in ARRAY
is returned. Otherwise, an array of rank n-1, where n equals the
rank of ARRAY, and a shape similar to that of ARRAY with dimension
DIM dropped is returned.
_Example_:
PROGRAM test_sum
INTEGER :: x(5) = (/ 1, 2, 3, 4 ,5 /)
print *, SUM(x) ! all elements, sum = 15
print *, SUM(x, MASK=MOD(x, 2)==1) ! odd elements, sum = 9
END PROGRAM
_See also_:
*note PRODUCT::

File: gfortran.info, Node: SYMLNK, Next: SYSTEM, Prev: SUM, Up: Intrinsic Procedures
9.263 `SYMLNK' -- Create a symbolic link
========================================
_Description_:
Makes a symbolic link from file PATH1 to PATH2. A null character
(`CHAR(0)') can be used to mark the end of the names in PATH1 and
PATH2; otherwise, trailing blanks in the file names are ignored.
If the STATUS argument is supplied, it contains 0 on success or a
nonzero error code upon return; see `symlink(2)'. If the system
does not supply `symlink(2)', `ENOSYS' is returned.
This intrinsic is provided in both subroutine and function forms;
however, only one form can be used in any given program unit.
_Standard_:
GNU extension
_Class_:
Subroutine, function
_Syntax_:
`CALL SYMLNK(PATH1, PATH2 [, STATUS])'
`STATUS = SYMLNK(PATH1, PATH2)'
_Arguments_:
PATH1 Shall be of default `CHARACTER' type.
PATH2 Shall be of default `CHARACTER' type.
STATUS (Optional) Shall be of default `INTEGER' type.
_See also_:
*note LINK::, *note UNLINK::

File: gfortran.info, Node: SYSTEM, Next: SYSTEM_CLOCK, Prev: SYMLNK, Up: Intrinsic Procedures
9.264 `SYSTEM' -- Execute a shell command
=========================================
_Description_:
Passes the command COMMAND to a shell (see `system(3)'). If
argument STATUS is present, it contains the value returned by
`system(3)', which is presumably 0 if the shell command succeeded.
Note that which shell is used to invoke the command is
system-dependent and environment-dependent.
This intrinsic is provided in both subroutine and function forms;
however, only one form can be used in any given program unit.
Note that the `system' function need not be thread-safe. It is the
responsibility of the user to ensure that `system' is not called
concurrently.
_Standard_:
GNU extension
_Class_:
Subroutine, function
_Syntax_:
`CALL SYSTEM(COMMAND [, STATUS])'
`STATUS = SYSTEM(COMMAND)'
_Arguments_:
COMMAND Shall be of default `CHARACTER' type.
STATUS (Optional) Shall be of default `INTEGER' type.
_See also_:
*note EXECUTE_COMMAND_LINE::, which is part of the Fortran 2008
standard and should considered in new code for future portability.

File: gfortran.info, Node: SYSTEM_CLOCK, Next: TAN, Prev: SYSTEM, Up: Intrinsic Procedures
9.265 `SYSTEM_CLOCK' -- Time function
=====================================
_Description_:
Determines the COUNT of a processor clock since an unspecified
time in the past modulo COUNT_MAX, COUNT_RATE determines the
number of clock ticks per second. If the platform supports a
monotonic clock, that clock is used and can, depending on the
platform clock implementation, provide up to nanosecond
resolution. If a monotonic clock is not available, the
implementation falls back to a realtime clock.
COUNT_RATE is system dependent and can vary depending on the kind
of the arguments. For KIND=4 arguments (and smaller integer kinds),
COUNT represents milliseconds, while for KIND=8 arguments (and
larger integer kinds), COUNT typically represents micro- or
nanoseconds depending on resolution of the underlying platform
clock. COUNT_MAX usually equals `HUGE(COUNT_MAX)'. Note that the
millisecond resolution of the KIND=4 version implies that the
COUNT will wrap around in roughly 25 days. In order to avoid issues
with the wrap around and for more precise timing, please use the
KIND=8 version.
If there is no clock, or querying the clock fails, COUNT is set to
`-HUGE(COUNT)', and COUNT_RATE and COUNT_MAX are set to zero.
When running on a platform using the GNU C library (glibc) version
2.16 or older, or a derivative thereof, the high resolution
monotonic clock is available only when linking with the RT
library. This can be done explicitly by adding the `-lrt' flag
when linking the application, but is also done implicitly when
using OpenMP.
On the Windows platform, the version with KIND=4 arguments uses
the `GetTickCount' function, whereas the KIND=8 version uses
`QueryPerformanceCounter' and `QueryPerformanceCounterFrequency'.
For more information, and potential caveats, please see the
platform documentation.
_Standard_:
Fortran 95 and later
_Class_:
Subroutine
_Syntax_:
`CALL SYSTEM_CLOCK([COUNT, COUNT_RATE, COUNT_MAX])'
_Arguments_:
COUNT (Optional) shall be a scalar of type `INTEGER'
with `INTENT(OUT)'.
COUNT_RATE (Optional) shall be a scalar of type `INTEGER'
or `REAL', with `INTENT(OUT)'.
COUNT_MAX (Optional) shall be a scalar of type `INTEGER'
with `INTENT(OUT)'.
_Example_:
PROGRAM test_system_clock
INTEGER :: count, count_rate, count_max
CALL SYSTEM_CLOCK(count, count_rate, count_max)
WRITE(*,*) count, count_rate, count_max
END PROGRAM
_See also_:
*note DATE_AND_TIME::, *note CPU_TIME::

File: gfortran.info, Node: TAN, Next: TAND, Prev: SYSTEM_CLOCK, Up: Intrinsic Procedures
9.266 `TAN' -- Tangent function
===============================
_Description_:
`TAN(X)' computes the tangent of X.
_Standard_:
Fortran 77 and later, for a complex argument Fortran 2008 or later
_Class_:
Elemental function
_Syntax_:
`RESULT = TAN(X)'
_Arguments_:
X The type shall be `REAL' or `COMPLEX'.
_Return value_:
The return value has same type and kind as X, and its value is in
radians.
_Example_:
program test_tan
real(8) :: x = 0.165_8
x = tan(x)
end program test_tan
_Specific names_:
Name Argument Return type Standard
`TAN(X)' `REAL(4) X' `REAL(4)' Fortran 95 and
later
`DTAN(X)' `REAL(8) X' `REAL(8)' Fortran 95 and
later
_See also_:
Inverse function: *note ATAN:: Degrees function: *note TAND::

File: gfortran.info, Node: TAND, Next: TANH, Prev: TAN, Up: Intrinsic Procedures
9.267 `TAND' -- Tangent function, degrees
=========================================
_Description_:
`TAND(X)' computes the tangent of X in degrees.
This function is for compatibility only and should be avoided in
favor of standard constructs wherever possible.
_Standard_:
GNU Extension, enabled with `-fdec-math'.
_Class_:
Elemental function
_Syntax_:
`RESULT = TAND(X)'
_Arguments_:
X The type shall be `REAL' or `COMPLEX'.
_Return value_:
The return value has same type and kind as X, and its value is in
degrees.
_Example_:
program test_tand
real(8) :: x = 0.165_8
x = tand(x)
end program test_tand
_Specific names_:
Name Argument Return type Standard
`TAND(X)' `REAL(4) X' `REAL(4)' GNU Extension
`DTAND(X)' `REAL(8) X' `REAL(8)' GNU Extension
_See also_:
Inverse function: *note ATAND:: Radians function: *note TAN::

File: gfortran.info, Node: TANH, Next: THIS_IMAGE, Prev: TAND, Up: Intrinsic Procedures
9.268 `TANH' -- Hyperbolic tangent function
===========================================
_Description_:
`TANH(X)' computes the hyperbolic tangent of X.
_Standard_:
Fortran 77 and later, for a complex argument Fortran 2008 or later
_Class_:
Elemental function
_Syntax_:
`X = TANH(X)'
_Arguments_:
X The type shall be `REAL' or `COMPLEX'.
_Return value_:
The return value has same type and kind as X. If X is complex, the
imaginary part of the result is in radians. If X is `REAL', the
return value lies in the range - 1 \leq tanh(x) \leq 1 .
_Example_:
program test_tanh
real(8) :: x = 2.1_8
x = tanh(x)
end program test_tanh
_Specific names_:
Name Argument Return type Standard
`TANH(X)' `REAL(4) X' `REAL(4)' Fortran 95 and
later
`DTANH(X)' `REAL(8) X' `REAL(8)' Fortran 95 and
later
_See also_:
*note ATANH::

File: gfortran.info, Node: THIS_IMAGE, Next: TIME, Prev: TANH, Up: Intrinsic Procedures
9.269 `THIS_IMAGE' -- Function that returns the cosubscript index of this image
===============================================================================
_Description_:
Returns the cosubscript for this image.
_Standard_:
Fortran 2008 and later. With DISTANCE argument, Technical
Specification (TS) 18508 or later
_Class_:
Transformational function
_Syntax_:
`RESULT = THIS_IMAGE()'
`RESULT = THIS_IMAGE(DISTANCE)'
`RESULT = THIS_IMAGE(COARRAY [, DIM])'
_Arguments_:
DISTANCE (optional, intent(in)) Nonnegative scalar
integer (not permitted together with COARRAY).
COARRAY Coarray of any type (optional; if DIM
present, required).
DIM default integer scalar (optional). If present,
DIM shall be between one and the corank of
COARRAY.
_Return value_:
Default integer. If COARRAY is not present, it is scalar; if
DISTANCE is not present or has value 0, its value is the image
index on the invoking image for the current team, for values
smaller or equal distance to the initial team, it returns the
image index on the ancestor team which has a distance of DISTANCE
from the invoking team. If DISTANCE is larger than the distance to
the initial team, the image index of the initial team is returned.
Otherwise when the COARRAY is present, if DIM is not present, a
rank-1 array with corank elements is returned, containing the
cosubscripts for COARRAY specifying the invoking image. If DIM is
present, a scalar is returned, with the value of the DIM element
of `THIS_IMAGE(COARRAY)'.
_Example_:
INTEGER :: value[*]
INTEGER :: i
value = THIS_IMAGE()
SYNC ALL
IF (THIS_IMAGE() == 1) THEN
DO i = 1, NUM_IMAGES()
WRITE(*,'(2(a,i0))') 'value[', i, '] is ', value[i]
END DO
END IF
! Check whether the current image is the initial image
IF (THIS_IMAGE(HUGE(1)) /= THIS_IMAGE())
error stop "something is rotten here"
_See also_:
*note NUM_IMAGES::, *note IMAGE_INDEX::

File: gfortran.info, Node: TIME, Next: TIME8, Prev: THIS_IMAGE, Up: Intrinsic Procedures
9.270 `TIME' -- Time function
=============================
_Description_:
Returns the current time encoded as an integer (in the manner of
the function `time(3)' in the C standard library). This value is
suitable for passing to *note CTIME::, *note GMTIME::, and *note
LTIME::.
This intrinsic is not fully portable, such as to systems with
32-bit `INTEGER' types but supporting times wider than 32 bits.
Therefore, the values returned by this intrinsic might be, or
become, negative, or numerically less than previous values, during
a single run of the compiled program.
See *note TIME8::, for information on a similar intrinsic that
might be portable to more GNU Fortran implementations, though to
fewer Fortran compilers.
_Standard_:
GNU extension
_Class_:
Function
_Syntax_:
`RESULT = TIME()'
_Return value_:
The return value is a scalar of type `INTEGER(4)'.
_See also_:
*note DATE_AND_TIME::, *note CTIME::, *note GMTIME::, *note
LTIME::, *note MCLOCK::, *note TIME8::

File: gfortran.info, Node: TIME8, Next: TINY, Prev: TIME, Up: Intrinsic Procedures
9.271 `TIME8' -- Time function (64-bit)
=======================================
_Description_:
Returns the current time encoded as an integer (in the manner of
the function `time(3)' in the C standard library). This value is
suitable for passing to *note CTIME::, *note GMTIME::, and *note
LTIME::.
_Warning:_ this intrinsic does not increase the range of the timing
values over that returned by `time(3)'. On a system with a 32-bit
`time(3)', `TIME8' will return a 32-bit value, even though it is
converted to a 64-bit `INTEGER(8)' value. That means overflows of
the 32-bit value can still occur. Therefore, the values returned
by this intrinsic might be or become negative or numerically less
than previous values during a single run of the compiled program.
_Standard_:
GNU extension
_Class_:
Function
_Syntax_:
`RESULT = TIME8()'
_Return value_:
The return value is a scalar of type `INTEGER(8)'.
_See also_:
*note DATE_AND_TIME::, *note CTIME::, *note GMTIME::, *note
LTIME::, *note MCLOCK8::, *note TIME::

File: gfortran.info, Node: TINY, Next: TRAILZ, Prev: TIME8, Up: Intrinsic Procedures
9.272 `TINY' -- Smallest positive number of a real kind
=======================================================
_Description_:
`TINY(X)' returns the smallest positive (non zero) number in the
model of the type of `X'.
_Standard_:
Fortran 95 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = TINY(X)'
_Arguments_:
X Shall be of type `REAL'.
_Return value_:
The return value is of the same type and kind as X
_Example_:
See `HUGE' for an example.

File: gfortran.info, Node: TRAILZ, Next: TRANSFER, Prev: TINY, Up: Intrinsic Procedures
9.273 `TRAILZ' -- Number of trailing zero bits of an integer
============================================================
_Description_:
`TRAILZ' returns the number of trailing zero bits of an integer.
_Standard_:
Fortran 2008 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = TRAILZ(I)'
_Arguments_:
I Shall be of type `INTEGER'.
_Return value_:
The type of the return value is the default `INTEGER'. If all the
bits of `I' are zero, the result value is `BIT_SIZE(I)'.
_Example_:
PROGRAM test_trailz
WRITE (*,*) TRAILZ(8) ! prints 3
END PROGRAM
_See also_:
*note BIT_SIZE::, *note LEADZ::, *note POPPAR::, *note POPCNT::

File: gfortran.info, Node: TRANSFER, Next: TRANSPOSE, Prev: TRAILZ, Up: Intrinsic Procedures
9.274 `TRANSFER' -- Transfer bit patterns
=========================================
_Description_:
Interprets the bitwise representation of SOURCE in memory as if it
is the representation of a variable or array of the same type and
type parameters as MOLD.
This is approximately equivalent to the C concept of _casting_ one
type to another.
_Standard_:
Fortran 95 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = TRANSFER(SOURCE, MOLD[, SIZE])'
_Arguments_:
SOURCE Shall be a scalar or an array of any type.
MOLD Shall be a scalar or an array of any type.
SIZE (Optional) shall be a scalar of type `INTEGER'.
_Return value_:
The result has the same type as MOLD, with the bit level
representation of SOURCE. If SIZE is present, the result is a
one-dimensional array of length SIZE. If SIZE is absent but MOLD
is an array (of any size or shape), the result is a one-
dimensional array of the minimum length needed to contain the
entirety of the bitwise representation of SOURCE. If SIZE is
absent and MOLD is a scalar, the result is a scalar.
If the bitwise representation of the result is longer than that of
SOURCE, then the leading bits of the result correspond to those of
SOURCE and any trailing bits are filled arbitrarily.
When the resulting bit representation does not correspond to a
valid representation of a variable of the same type as MOLD, the
results are undefined, and subsequent operations on the result
cannot be guaranteed to produce sensible behavior. For example,
it is possible to create `LOGICAL' variables for which `VAR' and
`.NOT.VAR' both appear to be true.
_Example_:
PROGRAM test_transfer
integer :: x = 2143289344
print *, transfer(x, 1.0) ! prints "NaN" on i686
END PROGRAM

File: gfortran.info, Node: TRANSPOSE, Next: TRIM, Prev: TRANSFER, Up: Intrinsic Procedures
9.275 `TRANSPOSE' -- Transpose an array of rank two
===================================================
_Description_:
Transpose an array of rank two. Element (i, j) of the result has
the value `MATRIX(j, i)', for all i, j.
_Standard_:
Fortran 95 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = TRANSPOSE(MATRIX)'
_Arguments_:
MATRIX Shall be an array of any type and have a rank
of two.
_Return value_:
The result has the same type as MATRIX, and has shape `(/ m, n /)'
if MATRIX has shape `(/ n, m /)'.

File: gfortran.info, Node: TRIM, Next: TTYNAM, Prev: TRANSPOSE, Up: Intrinsic Procedures
9.276 `TRIM' -- Remove trailing blank characters of a string
============================================================
_Description_:
Removes trailing blank characters of a string.
_Standard_:
Fortran 95 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = TRIM(STRING)'
_Arguments_:
STRING Shall be a scalar of type `CHARACTER'.
_Return value_:
A scalar of type `CHARACTER' which length is that of STRING less
the number of trailing blanks.
_Example_:
PROGRAM test_trim
CHARACTER(len=10), PARAMETER :: s = "GFORTRAN "
WRITE(*,*) LEN(s), LEN(TRIM(s)) ! "10 8", with/without trailing blanks
END PROGRAM
_See also_:
*note ADJUSTL::, *note ADJUSTR::

File: gfortran.info, Node: TTYNAM, Next: UBOUND, Prev: TRIM, Up: Intrinsic Procedures
9.277 `TTYNAM' -- Get the name of a terminal device.
====================================================
_Description_:
Get the name of a terminal device. For more information, see
`ttyname(3)'.
This intrinsic is provided in both subroutine and function forms;
however, only one form can be used in any given program unit.
_Standard_:
GNU extension
_Class_:
Subroutine, function
_Syntax_:
`CALL TTYNAM(UNIT, NAME)'
`NAME = TTYNAM(UNIT)'
_Arguments_:
UNIT Shall be a scalar `INTEGER'.
NAME Shall be of type `CHARACTER'.
_Example_:
PROGRAM test_ttynam
INTEGER :: unit
DO unit = 1, 10
IF (isatty(unit=unit)) write(*,*) ttynam(unit)
END DO
END PROGRAM
_See also_:
*note ISATTY::

File: gfortran.info, Node: UBOUND, Next: UCOBOUND, Prev: TTYNAM, Up: Intrinsic Procedures
9.278 `UBOUND' -- Upper dimension bounds of an array
====================================================
_Description_:
Returns the upper bounds of an array, or a single upper bound
along the DIM dimension.
_Standard_:
Fortran 95 and later, with KIND argument Fortran 2003 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = UBOUND(ARRAY [, DIM [, KIND]])'
_Arguments_:
ARRAY Shall be an array, of any type.
DIM (Optional) Shall be a scalar `INTEGER'.
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
_Return value_:
The return value is of type `INTEGER' and of kind KIND. If KIND is
absent, the return value is of default integer kind. If DIM is
absent, the result is an array of the upper bounds of ARRAY. If
DIM is present, the result is a scalar corresponding to the upper
bound of the array along that dimension. If ARRAY is an
expression rather than a whole array or array structure component,
or if it has a zero extent along the relevant dimension, the upper
bound is taken to be the number of elements along the relevant
dimension.
_See also_:
*note LBOUND::, *note LCOBOUND::

File: gfortran.info, Node: UCOBOUND, Next: UMASK, Prev: UBOUND, Up: Intrinsic Procedures
9.279 `UCOBOUND' -- Upper codimension bounds of an array
========================================================
_Description_:
Returns the upper cobounds of a coarray, or a single upper cobound
along the DIM codimension.
_Standard_:
Fortran 2008 and later
_Class_:
Inquiry function
_Syntax_:
`RESULT = UCOBOUND(COARRAY [, DIM [, KIND]])'
_Arguments_:
ARRAY Shall be an coarray, of any type.
DIM (Optional) Shall be a scalar `INTEGER'.
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
_Return value_:
The return value is of type `INTEGER' and of kind KIND. If KIND is
absent, the return value is of default integer kind. If DIM is
absent, the result is an array of the lower cobounds of COARRAY.
If DIM is present, the result is a scalar corresponding to the
lower cobound of the array along that codimension.
_See also_:
*note LCOBOUND::, *note LBOUND::

File: gfortran.info, Node: UMASK, Next: UNLINK, Prev: UCOBOUND, Up: Intrinsic Procedures
9.280 `UMASK' -- Set the file creation mask
===========================================
_Description_:
Sets the file creation mask to MASK. If called as a function, it
returns the old value. If called as a subroutine and argument OLD
if it is supplied, it is set to the old value. See `umask(2)'.
_Standard_:
GNU extension
_Class_:
Subroutine, function
_Syntax_:
`CALL UMASK(MASK [, OLD])'
`OLD = UMASK(MASK)'
_Arguments_:
MASK Shall be a scalar of type `INTEGER'.
OLD (Optional) Shall be a scalar of type `INTEGER'.

File: gfortran.info, Node: UNLINK, Next: UNPACK, Prev: UMASK, Up: Intrinsic Procedures
9.281 `UNLINK' -- Remove a file from the file system
====================================================
_Description_:
Unlinks the file PATH. A null character (`CHAR(0)') can be used to
mark the end of the name in PATH; otherwise, trailing blanks in
the file name are ignored. If the STATUS argument is supplied, it
contains 0 on success or a nonzero error code upon return; see
`unlink(2)'.
This intrinsic is provided in both subroutine and function forms;
however, only one form can be used in any given program unit.
_Standard_:
GNU extension
_Class_:
Subroutine, function
_Syntax_:
`CALL UNLINK(PATH [, STATUS])'
`STATUS = UNLINK(PATH)'
_Arguments_:
PATH Shall be of default `CHARACTER' type.
STATUS (Optional) Shall be of default `INTEGER' type.
_See also_:
*note LINK::, *note SYMLNK::

File: gfortran.info, Node: UNPACK, Next: VERIFY, Prev: UNLINK, Up: Intrinsic Procedures
9.282 `UNPACK' -- Unpack an array of rank one into an array
===========================================================
_Description_:
Store the elements of VECTOR in an array of higher rank.
_Standard_:
Fortran 95 and later
_Class_:
Transformational function
_Syntax_:
`RESULT = UNPACK(VECTOR, MASK, FIELD)'
_Arguments_:
VECTOR Shall be an array of any type and rank one. It
shall have at least as many elements as MASK
has `TRUE' values.
MASK Shall be an array of type `LOGICAL'.
FIELD Shall be of the same type as VECTOR and have
the same shape as MASK.
_Return value_:
The resulting array corresponds to FIELD with `TRUE' elements of
MASK replaced by values from VECTOR in array element order.
_Example_:
PROGRAM test_unpack
integer :: vector(2) = (/1,1/)
logical :: mask(4) = (/ .TRUE., .FALSE., .FALSE., .TRUE. /)
integer :: field(2,2) = 0, unity(2,2)
! result: unity matrix
unity = unpack(vector, reshape(mask, (/2,2/)), field)
END PROGRAM
_See also_:
*note PACK::, *note SPREAD::

File: gfortran.info, Node: VERIFY, Next: XOR, Prev: UNPACK, Up: Intrinsic Procedures
9.283 `VERIFY' -- Scan a string for characters not a given set
==============================================================
_Description_:
Verifies that all the characters in STRING belong to the set of
characters in SET.
If BACK is either absent or equals `FALSE', this function returns
the position of the leftmost character of STRING that is not in
SET. If BACK equals `TRUE', the rightmost position is returned. If
all characters of STRING are found in SET, the result is zero.
_Standard_:
Fortran 95 and later, with KIND argument Fortran 2003 and later
_Class_:
Elemental function
_Syntax_:
`RESULT = VERIFY(STRING, SET[, BACK [, KIND]])'
_Arguments_:
STRING Shall be of type `CHARACTER'.
SET Shall be of type `CHARACTER'.
BACK (Optional) shall be of type `LOGICAL'.
KIND (Optional) An `INTEGER' initialization
expression indicating the kind parameter of
the result.
_Return value_:
The return value is of type `INTEGER' and of kind KIND. If KIND is
absent, the return value is of default integer kind.
_Example_:
PROGRAM test_verify
WRITE(*,*) VERIFY("FORTRAN", "AO") ! 1, found 'F'
WRITE(*,*) VERIFY("FORTRAN", "FOO") ! 3, found 'R'
WRITE(*,*) VERIFY("FORTRAN", "C++") ! 1, found 'F'
WRITE(*,*) VERIFY("FORTRAN", "C++", .TRUE.) ! 7, found 'N'
WRITE(*,*) VERIFY("FORTRAN", "FORTRAN") ! 0' found none
END PROGRAM
_See also_:
*note SCAN::, *note INDEX intrinsic::

File: gfortran.info, Node: XOR, Prev: VERIFY, Up: Intrinsic Procedures
9.284 `XOR' -- Bitwise logical exclusive OR
===========================================
_Description_:
Bitwise logical exclusive or.
This intrinsic routine is provided for backwards compatibility with
GNU Fortran 77. For integer arguments, programmers should consider
the use of the *note IEOR:: intrinsic and for logical arguments the
`.NEQV.' operator, which are both defined by the Fortran standard.
_Standard_:
GNU extension
_Class_:
Function
_Syntax_:
`RESULT = XOR(I, J)'
_Arguments_:
I The type shall be either a scalar `INTEGER'
type or a scalar `LOGICAL' type or a
boz-literal-constant.
J The type shall be the same as the type of I or
a boz-literal-constant. I and J shall not both
be boz-literal-constants. If either I and J
is a boz-literal-constant, then the other
argument must be a scalar `INTEGER'.
_Return value_:
The return type is either a scalar `INTEGER' or a scalar
`LOGICAL'. If the kind type parameters differ, then the smaller
kind type is implicitly converted to larger kind, and the return
has the larger kind. A boz-literal-constant is converted to an
`INTEGER' with the kind type parameter of the other argument as-if
a call to *note INT:: occurred.
_Example_:
PROGRAM test_xor
LOGICAL :: T = .TRUE., F = .FALSE.
INTEGER :: a, b
DATA a / Z'F' /, b / Z'3' /
WRITE (*,*) XOR(T, T), XOR(T, F), XOR(F, T), XOR(F, F)
WRITE (*,*) XOR(a, b)
END PROGRAM
_See also_:
Fortran 95 elemental function: *note IEOR::

File: gfortran.info, Node: Intrinsic Modules, Next: Contributing, Prev: Intrinsic Procedures, Up: Top
10 Intrinsic Modules
********************
* Menu:
* ISO_FORTRAN_ENV::
* ISO_C_BINDING::
* IEEE modules::
* OpenMP Modules OMP_LIB and OMP_LIB_KINDS::
* OpenACC Module OPENACC::

File: gfortran.info, Node: ISO_FORTRAN_ENV, Next: ISO_C_BINDING, Up: Intrinsic Modules
10.1 `ISO_FORTRAN_ENV'
======================
_Standard_:
Fortran 2003 and later, except when otherwise noted
The `ISO_FORTRAN_ENV' module provides the following scalar
default-integer named constants:
`ATOMIC_INT_KIND':
Default-kind integer constant to be used as kind parameter when
defining integer variables used in atomic operations. (Fortran
2008 or later.)
`ATOMIC_LOGICAL_KIND':
Default-kind integer constant to be used as kind parameter when
defining logical variables used in atomic operations. (Fortran
2008 or later.)
`CHARACTER_KINDS':
Default-kind integer constant array of rank one containing the
supported kind parameters of the `CHARACTER' type. (Fortran 2008
or later.)
`CHARACTER_STORAGE_SIZE':
Size in bits of the character storage unit.
`ERROR_UNIT':
Identifies the preconnected unit used for error reporting.
`FILE_STORAGE_SIZE':
Size in bits of the file-storage unit.
`INPUT_UNIT':
Identifies the preconnected unit identified by the asterisk (`*')
in `READ' statement.
`INT8', `INT16', `INT32', `INT64':
Kind type parameters to specify an INTEGER type with a storage
size of 16, 32, and 64 bits. It is negative if a target platform
does not support the particular kind. (Fortran 2008 or later.)
`INTEGER_KINDS':
Default-kind integer constant array of rank one containing the
supported kind parameters of the `INTEGER' type. (Fortran 2008 or
later.)
`IOSTAT_END':
The value assigned to the variable passed to the `IOSTAT='
specifier of an input/output statement if an end-of-file condition
occurred.
`IOSTAT_EOR':
The value assigned to the variable passed to the `IOSTAT='
specifier of an input/output statement if an end-of-record
condition occurred.
`IOSTAT_INQUIRE_INTERNAL_UNIT':
Scalar default-integer constant, used by `INQUIRE' for the
`IOSTAT=' specifier to denote an that a unit number identifies an
internal unit. (Fortran 2008 or later.)
`NUMERIC_STORAGE_SIZE':
The size in bits of the numeric storage unit.
`LOGICAL_KINDS':
Default-kind integer constant array of rank one containing the
supported kind parameters of the `LOGICAL' type. (Fortran 2008 or
later.)
`OUTPUT_UNIT':
Identifies the preconnected unit identified by the asterisk (`*')
in `WRITE' statement.
`REAL32', `REAL64', `REAL128':
Kind type parameters to specify a REAL type with a storage size of
32, 64, and 128 bits. It is negative if a target platform does not
support the particular kind. (Fortran 2008 or later.)
`REAL_KINDS':
Default-kind integer constant array of rank one containing the
supported kind parameters of the `REAL' type. (Fortran 2008 or
later.)
`STAT_LOCKED':
Scalar default-integer constant used as STAT= return value by
`LOCK' to denote that the lock variable is locked by the executing
image. (Fortran 2008 or later.)
`STAT_LOCKED_OTHER_IMAGE':
Scalar default-integer constant used as STAT= return value by
`UNLOCK' to denote that the lock variable is locked by another
image. (Fortran 2008 or later.)
`STAT_STOPPED_IMAGE':
Positive, scalar default-integer constant used as STAT= return
value if the argument in the statement requires synchronisation
with an image, which has initiated the termination of the
execution. (Fortran 2008 or later.)
`STAT_FAILED_IMAGE':
Positive, scalar default-integer constant used as STAT= return
value if the argument in the statement requires communication with
an image, which has is in the failed state. (TS 18508 or later.)
`STAT_UNLOCKED':
Scalar default-integer constant used as STAT= return value by
`UNLOCK' to denote that the lock variable is unlocked. (Fortran
2008 or later.)
The module provides the following derived type:
`LOCK_TYPE':
Derived type with private components to be use with the `LOCK' and
`UNLOCK' statement. A variable of its type has to be always
declared as coarray and may not appear in a variable-definition
context. (Fortran 2008 or later.)
The module also provides the following intrinsic procedures: *note
COMPILER_OPTIONS:: and *note COMPILER_VERSION::.

File: gfortran.info, Node: ISO_C_BINDING, Next: IEEE modules, Prev: ISO_FORTRAN_ENV, Up: Intrinsic Modules
10.2 `ISO_C_BINDING'
====================
_Standard_:
Fortran 2003 and later, GNU extensions
The following intrinsic procedures are provided by the module; their
definition can be found in the section Intrinsic Procedures of this
manual.
`C_ASSOCIATED'
`C_F_POINTER'
`C_F_PROCPOINTER'
`C_FUNLOC'
`C_LOC'
`C_SIZEOF'
The `ISO_C_BINDING' module provides the following named constants of
type default integer, which can be used as KIND type parameters.
In addition to the integer named constants required by the Fortran
2003 standard and `C_PTRDIFF_T' of TS 29113, GNU Fortran provides as an
extension named constants for the 128-bit integer types supported by the
C compiler: `C_INT128_T, C_INT_LEAST128_T, C_INT_FAST128_T'.
Furthermore, if `__float128' is supported in C, the named constants
`C_FLOAT128, C_FLOAT128_COMPLEX' are defined.
Fortran Named constant C type Extension
Type
`INTEGER' `C_INT' `int'
`INTEGER' `C_SHORT' `short int'
`INTEGER' `C_LONG' `long int'
`INTEGER' `C_LONG_LONG' `long long int'
`INTEGER' `C_SIGNED_CHAR' `signed char'/`unsigned
char'
`INTEGER' `C_SIZE_T' `size_t'
`INTEGER' `C_INT8_T' `int8_t'
`INTEGER' `C_INT16_T' `int16_t'
`INTEGER' `C_INT32_T' `int32_t'
`INTEGER' `C_INT64_T' `int64_t'
`INTEGER' `C_INT128_T' `int128_t' Ext.
`INTEGER' `C_INT_LEAST8_T' `int_least8_t'
`INTEGER' `C_INT_LEAST16_T' `int_least16_t'
`INTEGER' `C_INT_LEAST32_T' `int_least32_t'
`INTEGER' `C_INT_LEAST64_T' `int_least64_t'
`INTEGER' `C_INT_LEAST128_T' `int_least128_t' Ext.
`INTEGER' `C_INT_FAST8_T' `int_fast8_t'
`INTEGER' `C_INT_FAST16_T' `int_fast16_t'
`INTEGER' `C_INT_FAST32_T' `int_fast32_t'
`INTEGER' `C_INT_FAST64_T' `int_fast64_t'
`INTEGER' `C_INT_FAST128_T' `int_fast128_t' Ext.
`INTEGER' `C_INTMAX_T' `intmax_t'
`INTEGER' `C_INTPTR_T' `intptr_t'
`INTEGER' `C_PTRDIFF_T' `ptrdiff_t' TS 29113
`REAL' `C_FLOAT' `float'
`REAL' `C_DOUBLE' `double'
`REAL' `C_LONG_DOUBLE' `long double'
`REAL' `C_FLOAT128' `__float128' Ext.
`COMPLEX' `C_FLOAT_COMPLEX' `float _Complex'
`COMPLEX' `C_DOUBLE_COMPLEX' `double _Complex'
`COMPLEX' `C_LONG_DOUBLE_COMPLEX' `long double _Complex'
`REAL' `C_FLOAT128_COMPLEX' `__float128 _Complex' Ext.
`LOGICAL' `C_BOOL' `_Bool'
`CHARACTER' `C_CHAR' `char'
Additionally, the following parameters of type
`CHARACTER(KIND=C_CHAR)' are defined.
Name C definition Value
`C_NULL_CHAR' null character `'\0''
`C_ALERT' alert `'\a''
`C_BACKSPACE' backspace `'\b''
`C_FORM_FEED' form feed `'\f''
`C_NEW_LINE' new line `'\n''
`C_CARRIAGE_RETURN'carriage return `'\r''
`C_HORIZONTAL_TAB'horizontal tab `'\t''
`C_VERTICAL_TAB'vertical tab `'\v''
Moreover, the following two named constants are defined:
Name Type
`C_NULL_PTR' `C_PTR'
`C_NULL_FUNPTR'`C_FUNPTR'
Both are equivalent to the value `NULL' in C.

File: gfortran.info, Node: IEEE modules, Next: OpenMP Modules OMP_LIB and OMP_LIB_KINDS, Prev: ISO_C_BINDING, Up: Intrinsic Modules
10.3 IEEE modules: `IEEE_EXCEPTIONS', `IEEE_ARITHMETIC', and `IEEE_FEATURES'
============================================================================
_Standard_:
Fortran 2003 and later
The `IEEE_EXCEPTIONS', `IEEE_ARITHMETIC', and `IEEE_FEATURES'
intrinsic modules provide support for exceptions and IEEE arithmetic, as
defined in Fortran 2003 and later standards, and the IEC 60559:1989
standard (_Binary floating-point arithmetic for microprocessor
systems_). These modules are only provided on the following supported
platforms:
* i386 and x86_64 processors
* platforms which use the GNU C Library (glibc)
* platforms with support for SysV/386 routines for floating point
interface (including Solaris and BSDs)
* platforms with the AIX OS
For full compliance with the Fortran standards, code using the
`IEEE_EXCEPTIONS' or `IEEE_ARITHMETIC' modules should be compiled with
the following options: `-fno-unsafe-math-optimizations -frounding-math
-fsignaling-nans'.

File: gfortran.info, Node: OpenMP Modules OMP_LIB and OMP_LIB_KINDS, Next: OpenACC Module OPENACC, Prev: IEEE modules, Up: Intrinsic Modules
10.4 OpenMP Modules `OMP_LIB' and `OMP_LIB_KINDS'
=================================================
_Standard_:
OpenMP Application Program Interface v4.5
The OpenMP Fortran runtime library routines are provided both in a
form of two Fortran 90 modules, named `OMP_LIB' and `OMP_LIB_KINDS',
and in a form of a Fortran `include' file named `omp_lib.h'. The
procedures provided by `OMP_LIB' can be found in the *note
Introduction: (libgomp)Top. manual, the named constants defined in the
modules are listed below.
For details refer to the actual OpenMP Application Program Interface
v4.5 (http://www.openmp.org/wp-content/uploads/openmp-4.5.pdf).
`OMP_LIB_KINDS' provides the following scalar default-integer named
constants:
`omp_lock_kind'
`omp_nest_lock_kind'
`omp_proc_bind_kind'
`omp_sched_kind'
`OMP_LIB' provides the scalar default-integer named constant
`openmp_version' with a value of the form YYYYMM, where `yyyy' is the
year and MM the month of the OpenMP version; for OpenMP v4.5 the value
is `201511'.
The following scalar integer named constants of the kind
`omp_sched_kind':
`omp_sched_static'
`omp_sched_dynamic'
`omp_sched_guided'
`omp_sched_auto'
And the following scalar integer named constants of the kind
`omp_proc_bind_kind':
`omp_proc_bind_false'
`omp_proc_bind_true'
`omp_proc_bind_master'
`omp_proc_bind_close'
`omp_proc_bind_spread'

File: gfortran.info, Node: OpenACC Module OPENACC, Prev: OpenMP Modules OMP_LIB and OMP_LIB_KINDS, Up: Intrinsic Modules
10.5 OpenACC Module `OPENACC'
=============================
_Standard_:
OpenACC Application Programming Interface v2.0
The OpenACC Fortran runtime library routines are provided both in a
form of a Fortran 90 module, named `OPENACC', and in form of a Fortran
`include' file named `openacc_lib.h'. The procedures provided by
`OPENACC' can be found in the *note Introduction: (libgomp)Top. manual,
the named constants defined in the modules are listed below.
For details refer to the actual OpenACC Application Programming
Interface v2.0 (http://www.openacc.org/).
`OPENACC' provides the scalar default-integer named constant
`openacc_version' with a value of the form YYYYMM, where `yyyy' is the
year and MM the month of the OpenACC version; for OpenACC v2.0 the
value is `201306'.

File: gfortran.info, Node: Contributing, Next: Copying, Prev: Intrinsic Modules, Up: Top
Contributing
************
Free software is only possible if people contribute to efforts to
create it. We're always in need of more people helping out with ideas
and comments, writing documentation and contributing code.
If you want to contribute to GNU Fortran, have a look at the long
lists of projects you can take on. Some of these projects are small,
some of them are large; some are completely orthogonal to the rest of
what is happening on GNU Fortran, but others are "mainstream" projects
in need of enthusiastic hackers. All of these projects are important!
We will eventually get around to the things here, but they are also
things doable by someone who is willing and able.
* Menu:
* Contributors::
* Projects::
* Proposed Extensions::

File: gfortran.info, Node: Contributors, Next: Projects, Up: Contributing
Contributors to GNU Fortran
===========================
Most of the parser was hand-crafted by _Andy Vaught_, who is also the
initiator of the whole project. Thanks Andy! Most of the interface
with GCC was written by _Paul Brook_.
The following individuals have contributed code and/or ideas and
significant help to the GNU Fortran project (in alphabetical order):
- Janne Blomqvist
- Steven Bosscher
- Paul Brook
- Tobias Burnus
- Franc,ois-Xavier Coudert
- Bud Davis
- Jerry DeLisle
- Erik Edelmann
- Bernhard Fischer
- Daniel Franke
- Richard Guenther
- Richard Henderson
- Katherine Holcomb
- Jakub Jelinek
- Niels Kristian Bech Jensen
- Steven Johnson
- Steven G. Kargl
- Thomas Koenig
- Asher Langton
- H. J. Lu
- Toon Moene
- Brooks Moses
- Andrew Pinski
- Tim Prince
- Christopher D. Rickett
- Richard Sandiford
- Tobias Schlu"ter
- Roger Sayle
- Paul Thomas
- Andy Vaught
- Feng Wang
- Janus Weil
- Daniel Kraft
The following people have contributed bug reports, smaller or larger
patches, and much needed feedback and encouragement for the GNU Fortran
project:
- Bill Clodius
- Dominique d'Humie`res
- Kate Hedstrom
- Erik Schnetter
- Joost VandeVondele
Many other individuals have helped debug, test and improve the GNU
Fortran compiler over the past few years, and we welcome you to do the
same! If you already have done so, and you would like to see your name
listed in the list above, please contact us.

File: gfortran.info, Node: Projects, Next: Proposed Extensions, Prev: Contributors, Up: Contributing
Projects
========
_Help build the test suite_
Solicit more code for donation to the test suite: the more
extensive the testsuite, the smaller the risk of breaking things
in the future! We can keep code private on request.
_Bug hunting/squishing_
Find bugs and write more test cases! Test cases are especially very
welcome, because it allows us to concentrate on fixing bugs
instead of isolating them. Going through the bugzilla database at
`https://gcc.gnu.org/bugzilla/' to reduce testcases posted there
and add more information (for example, for which version does the
testcase work, for which versions does it fail?) is also very
helpful.

File: gfortran.info, Node: Proposed Extensions, Prev: Projects, Up: Contributing
Proposed Extensions
===================
Here's a list of proposed extensions for the GNU Fortran compiler, in
no particular order. Most of these are necessary to be fully
compatible with existing Fortran compilers, but they are not part of
the official J3 Fortran 95 standard.
Compiler extensions:
--------------------
* User-specified alignment rules for structures.
* Automatically extend single precision constants to double.
* Compile code that conserves memory by dynamically allocating
common and module storage either on stack or heap.
* Compile flag to generate code for array conformance checking
(suggest -CC).
* User control of symbol names (underscores, etc).
* Compile setting for maximum size of stack frame size before
spilling parts to static or heap.
* Flag to force local variables into static space.
* Flag to force local variables onto stack.
Environment Options
-------------------
* Pluggable library modules for random numbers, linear algebra. LA
should use BLAS calling conventions.
* Environment variables controlling actions on arithmetic exceptions
like overflow, underflow, precision loss--Generate NaN, abort,
default. action.
* Set precision for fp units that support it (i387).
* Variable for setting fp rounding mode.
* Variable to fill uninitialized variables with a user-defined bit
pattern.
* Environment variable controlling filename that is opened for that
unit number.
* Environment variable to clear/trash memory being freed.
* Environment variable to control tracing of allocations and frees.
* Environment variable to display allocated memory at normal program
end.
* Environment variable for filename for * IO-unit.
* Environment variable for temporary file directory.
* Environment variable forcing standard output to be line buffered
(Unix).

File: gfortran.info, Node: Copying, Next: GNU Free Documentation License, Prev: Contributing, Up: Top
GNU General Public License
**************************
Version 3, 29 June 2007
Copyright (C) 2007 Free Software Foundation, Inc. `http://fsf.org/'
Everyone is permitted to copy and distribute verbatim copies of this
license document, but changing it is not allowed.
Preamble
========
The GNU General Public License is a free, copyleft license for software
and other kinds of works.
The licenses for most software and other practical works are designed
to take away your freedom to share and change the works. By contrast,
the GNU General Public License is intended to guarantee your freedom to
share and change all versions of a program-to make sure it remains free
software for all its users. We, the Free Software Foundation, use the
GNU General Public License for most of our software; it applies also to
any other work released this way by its authors. You can apply it to
your programs, too.
When we speak of free software, we are referring to freedom, not
price. Our General Public Licenses are designed to make sure that you
have the freedom to distribute copies of free software (and charge for
them if you wish), that you receive source code or can get it if you
want it, that you can change the software or use pieces of it in new
free programs, and that you know you can do these things.
To protect your rights, we need to prevent others from denying you
these rights or asking you to surrender the rights. Therefore, you
have certain responsibilities if you distribute copies of the software,
or if you modify it: responsibilities to respect the freedom of others.
For example, if you distribute copies of such a program, whether
gratis or for a fee, you must pass on to the recipients the same
freedoms that you received. You must make sure that they, too, receive
or can get the source code. And you must show them these terms so they
know their rights.
Developers that use the GNU GPL protect your rights with two steps:
(1) assert copyright on the software, and (2) offer you this License
giving you legal permission to copy, distribute and/or modify it.
For the developers' and authors' protection, the GPL clearly explains
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authors' sake, the GPL requires that modified versions be marked as
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Some devices are designed to deny users access to install or run
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aim of protecting users' freedom to change the software. The
systematic pattern of such abuse occurs in the area of products for
individuals to use, which is precisely where it is most unacceptable.
Therefore, we have designed this version of the GPL to prohibit the
practice for those products. If such problems arise substantially in
other domains, we stand ready to extend this provision to those domains
in future versions of the GPL, as needed to protect the freedom of
users.
Finally, every program is threatened constantly by software patents.
States should not allow patents to restrict development and use of
software on general-purpose computers, but in those that do, we wish to
avoid the special danger that patents applied to a free program could
make it effectively proprietary. To prevent this, the GPL assures that
patents cannot be used to render the program non-free.
The precise terms and conditions for copying, distribution and
modification follow.
TERMS AND CONDITIONS
====================
0. Definitions.
"This License" refers to version 3 of the GNU General Public
License.
"Copyright" also means copyright-like laws that apply to other
kinds of works, such as semiconductor masks.
"The Program" refers to any copyrightable work licensed under this
License. Each licensee is addressed as "you". "Licensees" and
"recipients" may be individuals or organizations.
To "modify" a work means to copy from or adapt all or part of the
work in a fashion requiring copyright permission, other than the
making of an exact copy. The resulting work is called a "modified
version" of the earlier work or a work "based on" the earlier work.
A "covered work" means either the unmodified Program or a work
based on the Program.
To "propagate" a work means to do anything with it that, without
permission, would make you directly or secondarily liable for
infringement under applicable copyright law, except executing it
on a computer or modifying a private copy. Propagation includes
copying, distribution (with or without modification), making
available to the public, and in some countries other activities as
well.
To "convey" a work means any kind of propagation that enables other
parties to make or receive copies. Mere interaction with a user
through a computer network, with no transfer of a copy, is not
conveying.
An interactive user interface displays "Appropriate Legal Notices"
to the extent that it includes a convenient and prominently visible
feature that (1) displays an appropriate copyright notice, and (2)
tells the user that there is no warranty for the work (except to
the extent that warranties are provided), that licensees may
convey the work under this License, and how to view a copy of this
License. If the interface presents a list of user commands or
options, such as a menu, a prominent item in the list meets this
criterion.
1. Source Code.
The "source code" for a work means the preferred form of the work
for making modifications to it. "Object code" means any
non-source form of a work.
A "Standard Interface" means an interface that either is an
official standard defined by a recognized standards body, or, in
the case of interfaces specified for a particular programming
language, one that is widely used among developers working in that
language.
The "System Libraries" of an executable work include anything,
other than the work as a whole, that (a) is included in the normal
form of packaging a Major Component, but which is not part of that
Major Component, and (b) serves only to enable use of the work
with that Major Component, or to implement a Standard Interface
for which an implementation is available to the public in source
code form. A "Major Component", in this context, means a major
essential component (kernel, window system, and so on) of the
specific operating system (if any) on which the executable work
runs, or a compiler used to produce the work, or an object code
interpreter used to run it.
The "Corresponding Source" for a work in object code form means all
the source code needed to generate, install, and (for an executable
work) run the object code and to modify the work, including
scripts to control those activities. However, it does not include
the work's System Libraries, or general-purpose tools or generally
available free programs which are used unmodified in performing
those activities but which are not part of the work. For example,
Corresponding Source includes interface definition files
associated with source files for the work, and the source code for
shared libraries and dynamically linked subprograms that the work
is specifically designed to require, such as by intimate data
communication or control flow between those subprograms and other
parts of the work.
The Corresponding Source need not include anything that users can
regenerate automatically from other parts of the Corresponding
Source.
The Corresponding Source for a work in source code form is that
same work.
2. Basic Permissions.
All rights granted under this License are granted for the term of
copyright on the Program, and are irrevocable provided the stated
conditions are met. This License explicitly affirms your unlimited
permission to run the unmodified Program. The output from running
a covered work is covered by this License only if the output,
given its content, constitutes a covered work. This License
acknowledges your rights of fair use or other equivalent, as
provided by copyright law.
You may make, run and propagate covered works that you do not
convey, without conditions so long as your license otherwise
remains in force. You may convey covered works to others for the
sole purpose of having them make modifications exclusively for
you, or provide you with facilities for running those works,
provided that you comply with the terms of this License in
conveying all material for which you do not control copyright.
Those thus making or running the covered works for you must do so
exclusively on your behalf, under your direction and control, on
terms that prohibit them from making any copies of your
copyrighted material outside their relationship with you.
Conveying under any other circumstances is permitted solely under
the conditions stated below. Sublicensing is not allowed; section
10 makes it unnecessary.
3. Protecting Users' Legal Rights From Anti-Circumvention Law.
No covered work shall be deemed part of an effective technological
measure under any applicable law fulfilling obligations under
article 11 of the WIPO copyright treaty adopted on 20 December
1996, or similar laws prohibiting or restricting circumvention of
such measures.
When you convey a covered work, you waive any legal power to forbid
circumvention of technological measures to the extent such
circumvention is effected by exercising rights under this License
with respect to the covered work, and you disclaim any intention
to limit operation or modification of the work as a means of
enforcing, against the work's users, your or third parties' legal
rights to forbid circumvention of technological measures.
4. Conveying Verbatim Copies.
You may convey verbatim copies of the Program's source code as you
receive it, in any medium, provided that you conspicuously and
appropriately publish on each copy an appropriate copyright notice;
keep intact all notices stating that this License and any
non-permissive terms added in accord with section 7 apply to the
code; keep intact all notices of the absence of any warranty; and
give all recipients a copy of this License along with the Program.
You may charge any price or no price for each copy that you convey,
and you may offer support or warranty protection for a fee.
5. Conveying Modified Source Versions.
You may convey a work based on the Program, or the modifications to
produce it from the Program, in the form of source code under the
terms of section 4, provided that you also meet all of these
conditions:
a. The work must carry prominent notices stating that you
modified it, and giving a relevant date.
b. The work must carry prominent notices stating that it is
released under this License and any conditions added under
section 7. This requirement modifies the requirement in
section 4 to "keep intact all notices".
c. You must license the entire work, as a whole, under this
License to anyone who comes into possession of a copy. This
License will therefore apply, along with any applicable
section 7 additional terms, to the whole of the work, and all
its parts, regardless of how they are packaged. This License
gives no permission to license the work in any other way, but
it does not invalidate such permission if you have separately
received it.
d. If the work has interactive user interfaces, each must display
Appropriate Legal Notices; however, if the Program has
interactive interfaces that do not display Appropriate Legal
Notices, your work need not make them do so.
A compilation of a covered work with other separate and independent
works, which are not by their nature extensions of the covered
work, and which are not combined with it such as to form a larger
program, in or on a volume of a storage or distribution medium, is
called an "aggregate" if the compilation and its resulting
copyright are not used to limit the access or legal rights of the
compilation's users beyond what the individual works permit.
Inclusion of a covered work in an aggregate does not cause this
License to apply to the other parts of the aggregate.
6. Conveying Non-Source Forms.
You may convey a covered work in object code form under the terms
of sections 4 and 5, provided that you also convey the
machine-readable Corresponding Source under the terms of this
License, in one of these ways:
a. Convey the object code in, or embodied in, a physical product
(including a physical distribution medium), accompanied by the
Corresponding Source fixed on a durable physical medium
customarily used for software interchange.
b. Convey the object code in, or embodied in, a physical product
(including a physical distribution medium), accompanied by a
written offer, valid for at least three years and valid for
as long as you offer spare parts or customer support for that
product model, to give anyone who possesses the object code
either (1) a copy of the Corresponding Source for all the
software in the product that is covered by this License, on a
durable physical medium customarily used for software
interchange, for a price no more than your reasonable cost of
physically performing this conveying of source, or (2) access
to copy the Corresponding Source from a network server at no
charge.
c. Convey individual copies of the object code with a copy of
the written offer to provide the Corresponding Source. This
alternative is allowed only occasionally and noncommercially,
and only if you received the object code with such an offer,
in accord with subsection 6b.
d. Convey the object code by offering access from a designated
place (gratis or for a charge), and offer equivalent access
to the Corresponding Source in the same way through the same
place at no further charge. You need not require recipients
to copy the Corresponding Source along with the object code.
If the place to copy the object code is a network server, the
Corresponding Source may be on a different server (operated
by you or a third party) that supports equivalent copying
facilities, provided you maintain clear directions next to
the object code saying where to find the Corresponding Source.
Regardless of what server hosts the Corresponding Source, you
remain obligated to ensure that it is available for as long
as needed to satisfy these requirements.
e. Convey the object code using peer-to-peer transmission,
provided you inform other peers where the object code and
Corresponding Source of the work are being offered to the
general public at no charge under subsection 6d.
A separable portion of the object code, whose source code is
excluded from the Corresponding Source as a System Library, need
not be included in conveying the object code work.
A "User Product" is either (1) a "consumer product", which means
any tangible personal property which is normally used for personal,
family, or household purposes, or (2) anything designed or sold for
incorporation into a dwelling. In determining whether a product
is a consumer product, doubtful cases shall be resolved in favor of
coverage. For a particular product received by a particular user,
"normally used" refers to a typical or common use of that class of
product, regardless of the status of the particular user or of the
way in which the particular user actually uses, or expects or is
expected to use, the product. A product is a consumer product
regardless of whether the product has substantial commercial,
industrial or non-consumer uses, unless such uses represent the
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"Installation Information" for a User Product means any methods,
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User Product from a modified version of its Corresponding Source.
The information must suffice to ensure that the continued
functioning of the modified object code is in no case prevented or
interfered with solely because modification has been made.
If you convey an object code work under this section in, or with,
or specifically for use in, a User Product, and the conveying
occurs as part of a transaction in which the right of possession
and use of the User Product is transferred to the recipient in
perpetuity or for a fixed term (regardless of how the transaction
is characterized), the Corresponding Source conveyed under this
section must be accompanied by the Installation Information. But
this requirement does not apply if neither you nor any third party
retains the ability to install modified object code on the User
Product (for example, the work has been installed in ROM).
The requirement to provide Installation Information does not
include a requirement to continue to provide support service,
warranty, or updates for a work that has been modified or
installed by the recipient, or for the User Product in which it
has been modified or installed. Access to a network may be denied
when the modification itself materially and adversely affects the
operation of the network or violates the rules and protocols for
communication across the network.
Corresponding Source conveyed, and Installation Information
provided, in accord with this section must be in a format that is
publicly documented (and with an implementation available to the
public in source code form), and must require no special password
or key for unpacking, reading or copying.
7. Additional Terms.
"Additional permissions" are terms that supplement the terms of
this License by making exceptions from one or more of its
conditions. Additional permissions that are applicable to the
entire Program shall be treated as though they were included in
this License, to the extent that they are valid under applicable
law. If additional permissions apply only to part of the Program,
that part may be used separately under those permissions, but the
entire Program remains governed by this License without regard to
the additional permissions.
When you convey a copy of a covered work, you may at your option
remove any additional permissions from that copy, or from any part
of it. (Additional permissions may be written to require their own
removal in certain cases when you modify the work.) You may place
additional permissions on material, added by you to a covered work,
for which you have or can give appropriate copyright permission.
Notwithstanding any other provision of this License, for material
you add to a covered work, you may (if authorized by the copyright
holders of that material) supplement the terms of this License
with terms:
a. Disclaiming warranty or limiting liability differently from
the terms of sections 15 and 16 of this License; or
b. Requiring preservation of specified reasonable legal notices
or author attributions in that material or in the Appropriate
Legal Notices displayed by works containing it; or
c. Prohibiting misrepresentation of the origin of that material,
or requiring that modified versions of such material be
marked in reasonable ways as different from the original
version; or
d. Limiting the use for publicity purposes of names of licensors
or authors of the material; or
e. Declining to grant rights under trademark law for use of some
trade names, trademarks, or service marks; or
f. Requiring indemnification of licensors and authors of that
material by anyone who conveys the material (or modified
versions of it) with contractual assumptions of liability to
the recipient, for any liability that these contractual
assumptions directly impose on those licensors and authors.
All other non-permissive additional terms are considered "further
restrictions" within the meaning of section 10. If the Program as
you received it, or any part of it, contains a notice stating that
it is governed by this License along with a term that is a further
restriction, you may remove that term. If a license document
contains a further restriction but permits relicensing or
conveying under this License, you may add to a covered work
material governed by the terms of that license document, provided
that the further restriction does not survive such relicensing or
conveying.
If you add terms to a covered work in accord with this section, you
must place, in the relevant source files, a statement of the
additional terms that apply to those files, or a notice indicating
where to find the applicable terms.
Additional terms, permissive or non-permissive, may be stated in
the form of a separately written license, or stated as exceptions;
the above requirements apply either way.
8. Termination.
You may not propagate or modify a covered work except as expressly
provided under this License. Any attempt otherwise to propagate or
modify it is void, and will automatically terminate your rights
under this License (including any patent licenses granted under
the third paragraph of section 11).
However, if you cease all violation of this License, then your
license from a particular copyright holder is reinstated (a)
provisionally, unless and until the copyright holder explicitly
and finally terminates your license, and (b) permanently, if the
copyright holder fails to notify you of the violation by some
reasonable means prior to 60 days after the cessation.
Moreover, your license from a particular copyright holder is
reinstated permanently if the copyright holder notifies you of the
violation by some reasonable means, this is the first time you have
received notice of violation of this License (for any work) from
that copyright holder, and you cure the violation prior to 30 days
after your receipt of the notice.
Termination of your rights under this section does not terminate
the licenses of parties who have received copies or rights from
you under this License. If your rights have been terminated and
not permanently reinstated, you do not qualify to receive new
licenses for the same material under section 10.
9. Acceptance Not Required for Having Copies.
You are not required to accept this License in order to receive or
run a copy of the Program. Ancillary propagation of a covered work
occurring solely as a consequence of using peer-to-peer
transmission to receive a copy likewise does not require
acceptance. However, nothing other than this License grants you
permission to propagate or modify any covered work. These actions
infringe copyright if you do not accept this License. Therefore,
by modifying or propagating a covered work, you indicate your
acceptance of this License to do so.
10. Automatic Licensing of Downstream Recipients.
Each time you convey a covered work, the recipient automatically
receives a license from the original licensors, to run, modify and
propagate that work, subject to this License. You are not
responsible for enforcing compliance by third parties with this
License.
An "entity transaction" is a transaction transferring control of an
organization, or substantially all assets of one, or subdividing an
organization, or merging organizations. If propagation of a
covered work results from an entity transaction, each party to that
transaction who receives a copy of the work also receives whatever
licenses to the work the party's predecessor in interest had or
could give under the previous paragraph, plus a right to
possession of the Corresponding Source of the work from the
predecessor in interest, if the predecessor has it or can get it
with reasonable efforts.
You may not impose any further restrictions on the exercise of the
rights granted or affirmed under this License. For example, you
may not impose a license fee, royalty, or other charge for
exercise of rights granted under this License, and you may not
initiate litigation (including a cross-claim or counterclaim in a
lawsuit) alleging that any patent claim is infringed by making,
using, selling, offering for sale, or importing the Program or any
portion of it.
11. Patents.
A "contributor" is a copyright holder who authorizes use under this
License of the Program or a work on which the Program is based.
The work thus licensed is called the contributor's "contributor
version".
A contributor's "essential patent claims" are all patent claims
owned or controlled by the contributor, whether already acquired or
hereafter acquired, that would be infringed by some manner,
permitted by this License, of making, using, or selling its
contributor version, but do not include claims that would be
infringed only as a consequence of further modification of the
contributor version. For purposes of this definition, "control"
includes the right to grant patent sublicenses in a manner
consistent with the requirements of this License.
Each contributor grants you a non-exclusive, worldwide,
royalty-free patent license under the contributor's essential
patent claims, to make, use, sell, offer for sale, import and
otherwise run, modify and propagate the contents of its
contributor version.
In the following three paragraphs, a "patent license" is any
express agreement or commitment, however denominated, not to
enforce a patent (such as an express permission to practice a
patent or covenant not to sue for patent infringement). To
"grant" such a patent license to a party means to make such an
agreement or commitment not to enforce a patent against the party.
If you convey a covered work, knowingly relying on a patent
license, and the Corresponding Source of the work is not available
for anyone to copy, free of charge and under the terms of this
License, through a publicly available network server or other
readily accessible means, then you must either (1) cause the
Corresponding Source to be so available, or (2) arrange to deprive
yourself of the benefit of the patent license for this particular
work, or (3) arrange, in a manner consistent with the requirements
of this License, to extend the patent license to downstream
recipients. "Knowingly relying" means you have actual knowledge
that, but for the patent license, your conveying the covered work
in a country, or your recipient's use of the covered work in a
country, would infringe one or more identifiable patents in that
country that you have reason to believe are valid.
If, pursuant to or in connection with a single transaction or
arrangement, you convey, or propagate by procuring conveyance of, a
covered work, and grant a patent license to some of the parties
receiving the covered work authorizing them to use, propagate,
modify or convey a specific copy of the covered work, then the
patent license you grant is automatically extended to all
recipients of the covered work and works based on it.
A patent license is "discriminatory" if it does not include within
the scope of its coverage, prohibits the exercise of, or is
conditioned on the non-exercise of one or more of the rights that
are specifically granted under this License. You may not convey a
covered work if you are a party to an arrangement with a third
party that is in the business of distributing software, under
which you make payment to the third party based on the extent of
your activity of conveying the work, and under which the third
party grants, to any of the parties who would receive the covered
work from you, a discriminatory patent license (a) in connection
with copies of the covered work conveyed by you (or copies made
from those copies), or (b) primarily for and in connection with
specific products or compilations that contain the covered work,
unless you entered into that arrangement, or that patent license
was granted, prior to 28 March 2007.
Nothing in this License shall be construed as excluding or limiting
any implied license or other defenses to infringement that may
otherwise be available to you under applicable patent law.
12. No Surrender of Others' Freedom.
If conditions are imposed on you (whether by court order,
agreement or otherwise) that contradict the conditions of this
License, they do not excuse you from the conditions of this
License. If you cannot convey a covered work so as to satisfy
simultaneously your obligations under this License and any other
pertinent obligations, then as a consequence you may not convey it
at all. For example, if you agree to terms that obligate you to
collect a royalty for further conveying from those to whom you
convey the Program, the only way you could satisfy both those
terms and this License would be to refrain entirely from conveying
the Program.
13. Use with the GNU Affero General Public License.
Notwithstanding any other provision of this License, you have
permission to link or combine any covered work with a work licensed
under version 3 of the GNU Affero General Public License into a
single combined work, and to convey the resulting work. The terms
of this License will continue to apply to the part which is the
covered work, but the special requirements of the GNU Affero
General Public License, section 13, concerning interaction through
a network will apply to the combination as such.
14. Revised Versions of this License.
The Free Software Foundation may publish revised and/or new
versions of the GNU General Public License from time to time.
Such new versions will be similar in spirit to the present
version, but may differ in detail to address new problems or
concerns.
Each version is given a distinguishing version number. If the
Program specifies that a certain numbered version of the GNU
General Public License "or any later version" applies to it, you
have the option of following the terms and conditions either of
that numbered version or of any later version published by the
Free Software Foundation. If the Program does not specify a
version number of the GNU General Public License, you may choose
any version ever published by the Free Software Foundation.
If the Program specifies that a proxy can decide which future
versions of the GNU General Public License can be used, that
proxy's public statement of acceptance of a version permanently
authorizes you to choose that version for the Program.
Later license versions may give you additional or different
permissions. However, no additional obligations are imposed on any
author or copyright holder as a result of your choosing to follow a
later version.
15. Disclaimer of Warranty.
THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE
COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS"
WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE
RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.
SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL
NECESSARY SERVICING, REPAIR OR CORRECTION.
16. Limitation of Liability.
IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN
WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES
AND/OR CONVEYS THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU
FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR
CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE
THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA
BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF
THE POSSIBILITY OF SUCH DAMAGES.
17. Interpretation of Sections 15 and 16.
If the disclaimer of warranty and limitation of liability provided
above cannot be given local legal effect according to their terms,
reviewing courts shall apply local law that most closely
approximates an absolute waiver of all civil liability in
connection with the Program, unless a warranty or assumption of
liability accompanies a copy of the Program in return for a fee.
END OF TERMS AND CONDITIONS
===========================
How to Apply These Terms to Your New Programs
=============================================
If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these
terms.
To do so, attach the following notices to the program. It is safest
to attach them to the start of each source file to most effectively
state the exclusion of warranty; and each file should have at least the
"copyright" line and a pointer to where the full notice is found.
ONE LINE TO GIVE THE PROGRAM'S NAME AND A BRIEF IDEA OF WHAT IT DOES.
Copyright (C) YEAR NAME OF AUTHOR
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see `http://www.gnu.org/licenses/'.
Also add information on how to contact you by electronic and paper
mail.
If the program does terminal interaction, make it output a short
notice like this when it starts in an interactive mode:
PROGRAM Copyright (C) YEAR NAME OF AUTHOR
This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
This is free software, and you are welcome to redistribute it
under certain conditions; type `show c' for details.
The hypothetical commands `show w' and `show c' should show the
appropriate parts of the General Public License. Of course, your
program's commands might be different; for a GUI interface, you would
use an "about box".
You should also get your employer (if you work as a programmer) or
school, if any, to sign a "copyright disclaimer" for the program, if
necessary. For more information on this, and how to apply and follow
the GNU GPL, see `http://www.gnu.org/licenses/'.
The GNU General Public License does not permit incorporating your
program into proprietary programs. If your program is a subroutine
library, you may consider it more useful to permit linking proprietary
applications with the library. If this is what you want to do, use the
GNU Lesser General Public License instead of this License. But first,
please read `http://www.gnu.org/philosophy/why-not-lgpl.html'.

File: gfortran.info, Node: GNU Free Documentation License, Next: Funding, Prev: Copying, Up: Top
GNU Free Documentation License
******************************
Version 1.3, 3 November 2008
Copyright (C) 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
`http://fsf.org/'
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
0. PREAMBLE
The purpose of this License is to make a manual, textbook, or other
functional and useful document "free" in the sense of freedom: to
assure everyone the effective freedom to copy and redistribute it,
with or without modifying it, either commercially or
noncommercially. Secondarily, this License preserves for the
author and publisher a way to get credit for their work, while not
being considered responsible for modifications made by others.
This License is a kind of "copyleft", which means that derivative
works of the document must themselves be free in the same sense.
It complements the GNU General Public License, which is a copyleft
license designed for free software.
We have designed this License in order to use it for manuals for
free software, because free software needs free documentation: a
free program should come with manuals providing the same freedoms
that the software does. But this License is not limited to
software manuals; it can be used for any textual work, regardless
of subject matter or whether it is published as a printed book.
We recommend this License principally for works whose purpose is
instruction or reference.
1. APPLICABILITY AND DEFINITIONS
This License applies to any manual or other work, in any medium,
that contains a notice placed by the copyright holder saying it
can be distributed under the terms of this License. Such a notice
grants a world-wide, royalty-free license, unlimited in duration,
to use that work under the conditions stated herein. The
"Document", below, refers to any such manual or work. Any member
of the public is a licensee, and is addressed as "you". You
accept the license if you copy, modify or distribute the work in a
way requiring permission under copyright law.
A "Modified Version" of the Document means any work containing the
Document or a portion of it, either copied verbatim, or with
modifications and/or translated into another language.
A "Secondary Section" is a named appendix or a front-matter section
of the Document that deals exclusively with the relationship of the
publishers or authors of the Document to the Document's overall
subject (or to related matters) and contains nothing that could
fall directly within that overall subject. (Thus, if the Document
is in part a textbook of mathematics, a Secondary Section may not
explain any mathematics.) The relationship could be a matter of
historical connection with the subject or with related matters, or
of legal, commercial, philosophical, ethical or political position
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The "Invariant Sections" are certain Secondary Sections whose
titles are designated, as being those of Invariant Sections, in
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The Document may contain zero Invariant Sections. If the Document
does not identify any Invariant Sections then there are none.
The "Cover Texts" are certain short passages of text that are
listed, as Front-Cover Texts or Back-Cover Texts, in the notice
that says that the Document is released under this License. A
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be at most 25 words.
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The "Title Page" means, for a printed book, the title page itself,
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material this License requires to appear in the title page. For
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The "publisher" means any person or entity that distributes copies
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stands for a specific section name mentioned below, such as
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To "Preserve the Title" of such a section when you modify the
Document means that it remains a section "Entitled XYZ" according
to this definition.
The Document may include Warranty Disclaimers next to the notice
which states that this License applies to the Document. These
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this License, but only as regards disclaiming warranties: any other
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2. VERBATIM COPYING
You may copy and distribute the Document in any medium, either
commercially or noncommercially, provided that this License, the
copyright notices, and the license notice saying this License
applies to the Document are reproduced in all copies, and that you
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and you may publicly display copies.
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If you publish printed copies (or copies in media that commonly
have printed covers) of the Document, numbering more than 100, and
the Document's license notice requires Cover Texts, you must
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these Cover Texts: Front-Cover Texts on the front cover, and
Back-Cover Texts on the back cover. Both covers must also clearly
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front cover must present the full title with all words of the
title equally prominent and visible. You may add other material
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satisfy these conditions, can be treated as verbatim copying in
other respects.
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legibly, you should put the first ones listed (as many as fit
reasonably) on the actual cover, and continue the rest onto
adjacent pages.
If you publish or distribute Opaque copies of the Document
numbering more than 100, you must either include a
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state in or with each Opaque copy a computer-network location from
which the general network-using public has access to download
using public-standard network protocols a complete Transparent
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latter option, you must take reasonably prudent steps, when you
begin distribution of Opaque copies in quantity, to ensure that
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It is requested, but not required, that you contact the authors of
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version of the Document.
4. MODIFICATIONS
You may copy and distribute a Modified Version of the Document
under the conditions of sections 2 and 3 above, provided that you
release the Modified Version under precisely this License, with
the Modified Version filling the role of the Document, thus
licensing distribution and modification of the Modified Version to
whoever possesses a copy of it. In addition, you must do these
things in the Modified Version:
A. Use in the Title Page (and on the covers, if any) a title
distinct from that of the Document, and from those of
previous versions (which should, if there were any, be listed
in the History section of the Document). You may use the
same title as a previous version if the original publisher of
that version gives permission.
B. List on the Title Page, as authors, one or more persons or
entities responsible for authorship of the modifications in
the Modified Version, together with at least five of the
principal authors of the Document (all of its principal
authors, if it has fewer than five), unless they release you
from this requirement.
C. State on the Title page the name of the publisher of the
Modified Version, as the publisher.
D. Preserve all the copyright notices of the Document.
E. Add an appropriate copyright notice for your modifications
adjacent to the other copyright notices.
F. Include, immediately after the copyright notices, a license
notice giving the public permission to use the Modified
Version under the terms of this License, in the form shown in
the Addendum below.
G. Preserve in that license notice the full lists of Invariant
Sections and required Cover Texts given in the Document's
license notice.
H. Include an unaltered copy of this License.
I. Preserve the section Entitled "History", Preserve its Title,
and add to it an item stating at least the title, year, new
authors, and publisher of the Modified Version as given on
the Title Page. If there is no section Entitled "History" in
the Document, create one stating the title, year, authors,
and publisher of the Document as given on its Title Page,
then add an item describing the Modified Version as stated in
the previous sentence.
J. Preserve the network location, if any, given in the Document
for public access to a Transparent copy of the Document, and
likewise the network locations given in the Document for
previous versions it was based on. These may be placed in
the "History" section. You may omit a network location for a
work that was published at least four years before the
Document itself, or if the original publisher of the version
it refers to gives permission.
K. For any section Entitled "Acknowledgements" or "Dedications",
Preserve the Title of the section, and preserve in the
section all the substance and tone of each of the contributor
acknowledgements and/or dedications given therein.
L. Preserve all the Invariant Sections of the Document,
unaltered in their text and in their titles. Section numbers
or the equivalent are not considered part of the section
titles.
M. Delete any section Entitled "Endorsements". Such a section
may not be included in the Modified Version.
N. Do not retitle any existing section to be Entitled
"Endorsements" or to conflict in title with any Invariant
Section.
O. Preserve any Warranty Disclaimers.
If the Modified Version includes new front-matter sections or
appendices that qualify as Secondary Sections and contain no
material copied from the Document, you may at your option
designate some or all of these sections as invariant. To do this,
add their titles to the list of Invariant Sections in the Modified
Version's license notice. These titles must be distinct from any
other section titles.
You may add a section Entitled "Endorsements", provided it contains
nothing but endorsements of your Modified Version by various
parties--for example, statements of peer review or that the text
has been approved by an organization as the authoritative
definition of a standard.
You may add a passage of up to five words as a Front-Cover Text,
and a passage of up to 25 words as a Back-Cover Text, to the end
of the list of Cover Texts in the Modified Version. Only one
passage of Front-Cover Text and one of Back-Cover Text may be
added by (or through arrangements made by) any one entity. If the
Document already includes a cover text for the same cover,
previously added by you or by arrangement made by the same entity
you are acting on behalf of, you may not add another; but you may
replace the old one, on explicit permission from the previous
publisher that added the old one.
The author(s) and publisher(s) of the Document do not by this
License give permission to use their names for publicity for or to
assert or imply endorsement of any Modified Version.
5. COMBINING DOCUMENTS
You may combine the Document with other documents released under
this License, under the terms defined in section 4 above for
modified versions, provided that you include in the combination
all of the Invariant Sections of all of the original documents,
unmodified, and list them all as Invariant Sections of your
combined work in its license notice, and that you preserve all
their Warranty Disclaimers.
The combined work need only contain one copy of this License, and
multiple identical Invariant Sections may be replaced with a single
copy. If there are multiple Invariant Sections with the same name
but different contents, make the title of each such section unique
by adding at the end of it, in parentheses, the name of the
original author or publisher of that section if known, or else a
unique number. Make the same adjustment to the section titles in
the list of Invariant Sections in the license notice of the
combined work.
In the combination, you must combine any sections Entitled
"History" in the various original documents, forming one section
Entitled "History"; likewise combine any sections Entitled
"Acknowledgements", and any sections Entitled "Dedications". You
must delete all sections Entitled "Endorsements."
6. COLLECTIONS OF DOCUMENTS
You may make a collection consisting of the Document and other
documents released under this License, and replace the individual
copies of this License in the various documents with a single copy
that is included in the collection, provided that you follow the
rules of this License for verbatim copying of each of the
documents in all other respects.
You may extract a single document from such a collection, and
distribute it individually under this License, provided you insert
a copy of this License into the extracted document, and follow
this License in all other respects regarding verbatim copying of
that document.
7. AGGREGATION WITH INDEPENDENT WORKS
A compilation of the Document or its derivatives with other
separate and independent documents or works, in or on a volume of
a storage or distribution medium, is called an "aggregate" if the
copyright resulting from the compilation is not used to limit the
legal rights of the compilation's users beyond what the individual
works permit. When the Document is included in an aggregate, this
License does not apply to the other works in the aggregate which
are not themselves derivative works of the Document.
If the Cover Text requirement of section 3 is applicable to these
copies of the Document, then if the Document is less than one half
of the entire aggregate, the Document's Cover Texts may be placed
on covers that bracket the Document within the aggregate, or the
electronic equivalent of covers if the Document is in electronic
form. Otherwise they must appear on printed covers that bracket
the whole aggregate.
8. TRANSLATION
Translation is considered a kind of modification, so you may
distribute translations of the Document under the terms of section
4. Replacing Invariant Sections with translations requires special
permission from their copyright holders, but you may include
translations of some or all Invariant Sections in addition to the
original versions of these Invariant Sections. You may include a
translation of this License, and all the license notices in the
Document, and any Warranty Disclaimers, provided that you also
include the original English version of this License and the
original versions of those notices and disclaimers. In case of a
disagreement between the translation and the original version of
this License or a notice or disclaimer, the original version will
prevail.
If a section in the Document is Entitled "Acknowledgements",
"Dedications", or "History", the requirement (section 4) to
Preserve its Title (section 1) will typically require changing the
actual title.
9. TERMINATION
You may not copy, modify, sublicense, or distribute the Document
except as expressly provided under this License. Any attempt
otherwise to copy, modify, sublicense, or distribute it is void,
and will automatically terminate your rights under this License.
However, if you cease all violation of this License, then your
license from a particular copyright holder is reinstated (a)
provisionally, unless and until the copyright holder explicitly
and finally terminates your license, and (b) permanently, if the
copyright holder fails to notify you of the violation by some
reasonable means prior to 60 days after the cessation.
Moreover, your license from a particular copyright holder is
reinstated permanently if the copyright holder notifies you of the
violation by some reasonable means, this is the first time you have
received notice of violation of this License (for any work) from
that copyright holder, and you cure the violation prior to 30 days
after your receipt of the notice.
Termination of your rights under this section does not terminate
the licenses of parties who have received copies or rights from
you under this License. If your rights have been terminated and
not permanently reinstated, receipt of a copy of some or all of
the same material does not give you any rights to use it.
10. FUTURE REVISIONS OF THIS LICENSE
The Free Software Foundation may publish new, revised versions of
the GNU Free Documentation License from time to time. Such new
versions will be similar in spirit to the present version, but may
differ in detail to address new problems or concerns. See
`http://www.gnu.org/copyleft/'.
Each version of the License is given a distinguishing version
number. If the Document specifies that a particular numbered
version of this License "or any later version" applies to it, you
have the option of following the terms and conditions either of
that specified version or of any later version that has been
published (not as a draft) by the Free Software Foundation. If
the Document does not specify a version number of this License,
you may choose any version ever published (not as a draft) by the
Free Software Foundation. If the Document specifies that a proxy
can decide which future versions of this License can be used, that
proxy's public statement of acceptance of a version permanently
authorizes you to choose that version for the Document.
11. RELICENSING
"Massive Multiauthor Collaboration Site" (or "MMC Site") means any
World Wide Web server that publishes copyrightable works and also
provides prominent facilities for anybody to edit those works. A
public wiki that anybody can edit is an example of such a server.
A "Massive Multiauthor Collaboration" (or "MMC") contained in the
site means any set of copyrightable works thus published on the MMC
site.
"CC-BY-SA" means the Creative Commons Attribution-Share Alike 3.0
license published by Creative Commons Corporation, a not-for-profit
corporation with a principal place of business in San Francisco,
California, as well as future copyleft versions of that license
published by that same organization.
"Incorporate" means to publish or republish a Document, in whole or
in part, as part of another Document.
An MMC is "eligible for relicensing" if it is licensed under this
License, and if all works that were first published under this
License somewhere other than this MMC, and subsequently
incorporated in whole or in part into the MMC, (1) had no cover
texts or invariant sections, and (2) were thus incorporated prior
to November 1, 2008.
The operator of an MMC Site may republish an MMC contained in the
site under CC-BY-SA on the same site at any time before August 1,
2009, provided the MMC is eligible for relicensing.
ADDENDUM: How to use this License for your documents
====================================================
To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and license
notices just after the title page:
Copyright (C) YEAR YOUR NAME.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3
or any later version published by the Free Software Foundation;
with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
Texts. A copy of the license is included in the section entitled ``GNU
Free Documentation License''.
If you have Invariant Sections, Front-Cover Texts and Back-Cover
Texts, replace the "with...Texts." line with this:
with the Invariant Sections being LIST THEIR TITLES, with
the Front-Cover Texts being LIST, and with the Back-Cover Texts
being LIST.
If you have Invariant Sections without Cover Texts, or some other
combination of the three, merge those two alternatives to suit the
situation.
If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of
free software license, such as the GNU General Public License, to
permit their use in free software.

File: gfortran.info, Node: Funding, Next: Option Index, Prev: GNU Free Documentation License, Up: Top
Funding Free Software
*********************
If you want to have more free software a few years from now, it makes
sense for you to help encourage people to contribute funds for its
development. The most effective approach known is to encourage
commercial redistributors to donate.
Users of free software systems can boost the pace of development by
encouraging for-a-fee distributors to donate part of their selling price
to free software developers--the Free Software Foundation, and others.
The way to convince distributors to do this is to demand it and
expect it from them. So when you compare distributors, judge them
partly by how much they give to free software development. Show
distributors they must compete to be the one who gives the most.
To make this approach work, you must insist on numbers that you can
compare, such as, "We will donate ten dollars to the Frobnitz project
for each disk sold." Don't be satisfied with a vague promise, such as
"A portion of the profits are donated," since it doesn't give a basis
for comparison.
Even a precise fraction "of the profits from this disk" is not very
meaningful, since creative accounting and unrelated business decisions
can greatly alter what fraction of the sales price counts as profit.
If the price you pay is $50, ten percent of the profit is probably less
than a dollar; it might be a few cents, or nothing at all.
Some redistributors do development work themselves. This is useful
too; but to keep everyone honest, you need to inquire how much they do,
and what kind. Some kinds of development make much more long-term
difference than others. For example, maintaining a separate version of
a program contributes very little; maintaining the standard version of a
program for the whole community contributes much. Easy new ports
contribute little, since someone else would surely do them; difficult
ports such as adding a new CPU to the GNU Compiler Collection
contribute more; major new features or packages contribute the most.
By establishing the idea that supporting further development is "the
proper thing to do" when distributing free software for a fee, we can
assure a steady flow of resources into making more free software.
Copyright (C) 1994 Free Software Foundation, Inc.
Verbatim copying and redistribution of this section is permitted
without royalty; alteration is not permitted.

File: gfortran.info, Node: Option Index, Next: Keyword Index, Prev: Funding, Up: Top
Option Index
************
`gfortran''s command line options are indexed here without any initial
`-' or `--'. Where an option has both positive and negative forms
(such as -foption and -fno-option), relevant entries in the manual are
indexed under the most appropriate form; it may sometimes be useful to
look up both forms.
�[index�]
* Menu:
* A-PREDICATE=ANSWER: Preprocessing Options.
(line 120)
* APREDICATE=ANSWER: Preprocessing Options.
(line 114)
* backslash: Fortran Dialect Options.
(line 79)
* C: Preprocessing Options.
(line 123)
* c-prototypes: Interoperability Options.
(line 7)
* c-prototypes-external: Interoperability Options.
(line 25)
* CC: Preprocessing Options.
(line 138)
* cpp: Preprocessing Options.
(line 12)
* dD: Preprocessing Options.
(line 35)
* dI: Preprocessing Options.
(line 51)
* dM: Preprocessing Options.
(line 26)
* dN: Preprocessing Options.
(line 41)
* DNAME: Preprocessing Options.
(line 153)
* DNAME=DEFINITION: Preprocessing Options.
(line 156)
* dU: Preprocessing Options.
(line 44)
* faggressive-function-elimination: Code Gen Options. (line 411)
* falign-commons: Code Gen Options. (line 384)
* fall-intrinsics: Fortran Dialect Options.
(line 17)
* fblas-matmul-limit: Code Gen Options. (line 310)
* fbounds-check: Code Gen Options. (line 202)
* fcheck: Code Gen Options. (line 146)
* fcheck-array-temporaries: Code Gen Options. (line 237)
* fcoarray: Code Gen Options. (line 132)
* fconvert=CONVERSION: Runtime Options. (line 10)
* fcray-pointer: Fortran Dialect Options.
(line 134)
* fd-lines-as-code: Fortran Dialect Options.
(line 27)
* fd-lines-as-comments: Fortran Dialect Options.
(line 27)
* fdec: Fortran Dialect Options.
(line 34)
* fdec-include: Fortran Dialect Options.
(line 68)
* fdec-intrinsic-ints: Fortran Dialect Options.
(line 54)
* fdec-math: Fortran Dialect Options.
(line 59)
* fdec-static: Fortran Dialect Options.
(line 64)
* fdec-structure: Fortran Dialect Options.
(line 48)
* fdefault-double-8: Fortran Dialect Options.
(line 206)
* fdefault-integer-8: Fortran Dialect Options.
(line 170)
* fdefault-real-10: Fortran Dialect Options.
(line 186)
* fdefault-real-16: Fortran Dialect Options.
(line 196)
* fdefault-real-8: Fortran Dialect Options.
(line 176)
* fdollar-ok: Fortran Dialect Options.
(line 73)
* fdump-fortran-global: Debugging Options. (line 33)
* fdump-fortran-optimized: Debugging Options. (line 18)
* fdump-fortran-original: Debugging Options. (line 10)
* fdump-parse-tree: Debugging Options. (line 25)
* fexternal-blas: Code Gen Options. (line 302)
* ff2c: Code Gen Options. (line 28)
* ffixed-form: Fortran Dialect Options.
(line 11)
* ffixed-line-length-N: Fortran Dialect Options.
(line 96)
* ffpe-summary=LIST: Debugging Options. (line 74)
* ffpe-trap=LIST: Debugging Options. (line 40)
* ffree-form: Fortran Dialect Options.
(line 11)
* ffree-line-length-N: Fortran Dialect Options.
(line 118)
* fimplicit-none: Fortran Dialect Options.
(line 129)
* finit-character: Code Gen Options. (line 345)
* finit-derived: Code Gen Options. (line 345)
* finit-integer: Code Gen Options. (line 345)
* finit-local-zero: Code Gen Options. (line 345)
* finit-logical: Code Gen Options. (line 345)
* finit-real: Code Gen Options. (line 345)
* finline-matmul-limit: Code Gen Options. (line 321)
* finteger-4-integer-8: Fortran Dialect Options.
(line 214)
* fintrinsic-modules-path DIR: Directory Options. (line 36)
* fmax-array-constructor: Code Gen Options. (line 240)
* fmax-errors=N: Error and Warning Options.
(line 27)
* fmax-identifier-length=N: Fortran Dialect Options.
(line 125)
* fmax-stack-var-size: Code Gen Options. (line 258)
* fmax-subrecord-length=LENGTH: Runtime Options. (line 29)
* fmodule-private: Fortran Dialect Options.
(line 91)
* fno-automatic: Code Gen Options. (line 15)
* fno-backtrace: Debugging Options. (line 87)
* fno-protect-parens: Code Gen Options. (line 396)
* fno-underscoring: Code Gen Options. (line 57)
* fopenacc: Fortran Dialect Options.
(line 138)
* fopenmp: Fortran Dialect Options.
(line 150)
* fpack-derived: Code Gen Options. (line 280)
* fpad-source: Fortran Dialect Options.
(line 110)
* fpp: Preprocessing Options.
(line 12)
* frange-check: Fortran Dialect Options.
(line 158)
* freal-4-real-10: Fortran Dialect Options.
(line 230)
* freal-4-real-16: Fortran Dialect Options.
(line 230)
* freal-4-real-8: Fortran Dialect Options.
(line 230)
* freal-8-real-10: Fortran Dialect Options.
(line 230)
* freal-8-real-16: Fortran Dialect Options.
(line 230)
* freal-8-real-4: Fortran Dialect Options.
(line 230)
* frealloc-lhs: Code Gen Options. (line 405)
* frecord-marker=LENGTH: Runtime Options. (line 21)
* frecursive: Code Gen Options. (line 335)
* frepack-arrays: Code Gen Options. (line 286)
* frontend-loop-interchange: Code Gen Options. (line 436)
* frontend-optimize: Code Gen Options. (line 419)
* fsecond-underscore: Code Gen Options. (line 115)
* fshort-enums <1>: Fortran 2003 status. (line 92)
* fshort-enums: Code Gen Options. (line 296)
* fsign-zero: Runtime Options. (line 34)
* fstack-arrays: Code Gen Options. (line 272)
* fsyntax-only: Error and Warning Options.
(line 33)
* ftest-forall-temp: Fortran Dialect Options.
(line 260)
* fworking-directory: Preprocessing Options.
(line 55)
* H: Preprocessing Options.
(line 176)
* IDIR: Directory Options. (line 14)
* idirafter DIR: Preprocessing Options.
(line 70)
* imultilib DIR: Preprocessing Options.
(line 77)
* iprefix PREFIX: Preprocessing Options.
(line 81)
* iquote DIR: Preprocessing Options.
(line 90)
* isysroot DIR: Preprocessing Options.
(line 86)
* isystem DIR: Preprocessing Options.
(line 97)
* JDIR: Directory Options. (line 29)
* MDIR: Directory Options. (line 29)
* nostdinc: Preprocessing Options.
(line 105)
* P: Preprocessing Options.
(line 181)
* pedantic: Error and Warning Options.
(line 39)
* pedantic-errors: Error and Warning Options.
(line 58)
* static-libgfortran: Link Options. (line 11)
* std=STD option: Fortran Dialect Options.
(line 241)
* tail-call-workaround: Code Gen Options. (line 206)
* UNAME: Preprocessing Options.
(line 187)
* undef: Preprocessing Options.
(line 110)
* Waliasing: Error and Warning Options.
(line 71)
* Walign-commons: Error and Warning Options.
(line 226)
* Wall: Error and Warning Options.
(line 62)
* Wampersand: Error and Warning Options.
(line 88)
* Wargument-mismatch: Error and Warning Options.
(line 96)
* Warray-temporaries: Error and Warning Options.
(line 101)
* Wc-binding-type: Error and Warning Options.
(line 106)
* Wcharacter-truncation: Error and Warning Options.
(line 113)
* Wcompare-reals: Error and Warning Options.
(line 255)
* Wconversion: Error and Warning Options.
(line 122)
* Wconversion-extra: Error and Warning Options.
(line 126)
* Wdo-subscript: Error and Warning Options.
(line 267)
* Werror: Error and Warning Options.
(line 279)
* Wextra: Error and Warning Options.
(line 130)
* Wfrontend-loop-interchange: Error and Warning Options.
(line 135)
* Wfunction-elimination: Error and Warning Options.
(line 232)
* Wimplicit-interface: Error and Warning Options.
(line 139)
* Wimplicit-procedure: Error and Warning Options.
(line 145)
* Winteger-division: Error and Warning Options.
(line 149)
* Wintrinsic-shadow: Error and Warning Options.
(line 204)
* Wintrinsics-std: Error and Warning Options.
(line 153)
* Wline-truncation: Error and Warning Options.
(line 116)
* Wpedantic: Error and Warning Options.
(line 39)
* Wreal-q-constant: Error and Warning Options.
(line 160)
* Wrealloc-lhs: Error and Warning Options.
(line 237)
* Wrealloc-lhs-all: Error and Warning Options.
(line 250)
* Wsurprising: Error and Warning Options.
(line 164)
* Wtabs: Error and Warning Options.
(line 186)
* Wtargt-lifetime: Error and Warning Options.
(line 259)
* Wundefined-do-loop: Error and Warning Options.
(line 194)
* Wunderflow: Error and Warning Options.
(line 199)
* Wunused-dummy-argument: Error and Warning Options.
(line 215)
* Wunused-parameter: Error and Warning Options.
(line 219)
* Wuse-without-only: Error and Warning Options.
(line 211)
* Wzerotrip: Error and Warning Options.
(line 263)

File: gfortran.info, Node: Keyword Index, Prev: Option Index, Up: Top
Keyword Index
*************
�[index�]
* Menu:
* $: Fortran Dialect Options.
(line 73)
* %LOC: Argument list functions.
(line 6)
* %REF: Argument list functions.
(line 6)
* %VAL: Argument list functions.
(line 6)
* &: Error and Warning Options.
(line 88)
* [...]: Fortran 2003 status. (line 78)
* _gfortran_set_args: _gfortran_set_args. (line 6)
* _gfortran_set_convert: _gfortran_set_convert.
(line 6)
* _gfortran_set_fpe: _gfortran_set_fpe. (line 6)
* _gfortran_set_max_subrecord_length: _gfortran_set_max_subrecord_length.
(line 6)
* _gfortran_set_options: _gfortran_set_options.
(line 6)
* _gfortran_set_record_marker: _gfortran_set_record_marker.
(line 6)
* ABORT: ABORT. (line 6)
* ABS: ABS. (line 6)
* absolute value: ABS. (line 6)
* ACCESS: ACCESS. (line 6)
* ACCESS='STREAM' I/O: Fortran 2003 status. (line 104)
* ACHAR: ACHAR. (line 6)
* ACOS: ACOS. (line 6)
* ACOSD: ACOSD. (line 6)
* ACOSH: ACOSH. (line 6)
* adjust string <1>: ADJUSTR. (line 6)
* adjust string: ADJUSTL. (line 6)
* ADJUSTL: ADJUSTL. (line 6)
* ADJUSTR: ADJUSTR. (line 6)
* AIMAG: AIMAG. (line 6)
* AINT: AINT. (line 6)
* ALARM: ALARM. (line 6)
* ALGAMA: LOG_GAMMA. (line 6)
* aliasing: Error and Warning Options.
(line 71)
* alignment of COMMON blocks <1>: Code Gen Options. (line 384)
* alignment of COMMON blocks: Error and Warning Options.
(line 226)
* ALL: ALL. (line 6)
* all warnings: Error and Warning Options.
(line 62)
* ALLOCATABLE components of derived types: Fortran 2003 status.
(line 102)
* ALLOCATABLE dummy arguments: Fortran 2003 status. (line 98)
* ALLOCATABLE function results: Fortran 2003 status. (line 100)
* ALLOCATED: ALLOCATED. (line 6)
* allocation, moving: MOVE_ALLOC. (line 6)
* allocation, status: ALLOCATED. (line 6)
* ALOG: LOG. (line 6)
* ALOG10: LOG10. (line 6)
* AMAX0: MAX. (line 6)
* AMAX1: MAX. (line 6)
* AMIN0: MIN. (line 6)
* AMIN1: MIN. (line 6)
* AMOD: MOD. (line 6)
* AND: AND. (line 6)
* ANINT: ANINT. (line 6)
* ANY: ANY. (line 6)
* area hyperbolic cosine: ACOSH. (line 6)
* area hyperbolic sine: ASINH. (line 6)
* area hyperbolic tangent: ATANH. (line 6)
* argument list functions: Argument list functions.
(line 6)
* arguments, to program <1>: IARGC. (line 6)
* arguments, to program <2>: GET_COMMAND_ARGUMENT.
(line 6)
* arguments, to program <3>: GET_COMMAND. (line 6)
* arguments, to program <4>: GETARG. (line 6)
* arguments, to program: COMMAND_ARGUMENT_COUNT.
(line 6)
* array, add elements: SUM. (line 6)
* array, AND: IALL. (line 6)
* array, apply condition <1>: ANY. (line 6)
* array, apply condition: ALL. (line 6)
* array, bounds checking: Code Gen Options. (line 146)
* array, change dimensions: RESHAPE. (line 6)
* array, combine arrays: MERGE. (line 6)
* array, condition testing <1>: ANY. (line 6)
* array, condition testing: ALL. (line 6)
* array, conditionally add elements: SUM. (line 6)
* array, conditionally count elements: COUNT. (line 6)
* array, conditionally multiply elements: PRODUCT. (line 6)
* array, constructors: Fortran 2003 status. (line 78)
* array, contiguity: IS_CONTIGUOUS. (line 6)
* array, count elements: SIZE. (line 6)
* array, duplicate dimensions: SPREAD. (line 6)
* array, duplicate elements: SPREAD. (line 6)
* array, element counting: COUNT. (line 6)
* array, gather elements: PACK. (line 6)
* array, increase dimension <1>: UNPACK. (line 6)
* array, increase dimension: SPREAD. (line 6)
* array, indices of type real: Real array indices. (line 6)
* array, location of maximum element: MAXLOC. (line 6)
* array, location of minimum element: MINLOC. (line 6)
* array, lower bound: LBOUND. (line 6)
* array, maximum value: MAXVAL. (line 6)
* array, merge arrays: MERGE. (line 6)
* array, minimum value: MINVAL. (line 6)
* array, multiply elements: PRODUCT. (line 6)
* array, number of elements <1>: SIZE. (line 6)
* array, number of elements: COUNT. (line 6)
* array, OR: IANY. (line 6)
* array, packing: PACK. (line 6)
* array, parity: IPARITY. (line 6)
* array, permutation: CSHIFT. (line 6)
* array, product: PRODUCT. (line 6)
* array, reduce dimension: PACK. (line 6)
* array, rotate: CSHIFT. (line 6)
* array, scatter elements: UNPACK. (line 6)
* array, shape: SHAPE. (line 6)
* array, shift: EOSHIFT. (line 6)
* array, shift circularly: CSHIFT. (line 6)
* array, size: SIZE. (line 6)
* array, sum: SUM. (line 6)
* array, transmogrify: RESHAPE. (line 6)
* array, transpose: TRANSPOSE. (line 6)
* array, unpacking: UNPACK. (line 6)
* array, upper bound: UBOUND. (line 6)
* array, XOR: IPARITY. (line 6)
* ASCII collating sequence <1>: IACHAR. (line 6)
* ASCII collating sequence: ACHAR. (line 6)
* ASIN: ASIN. (line 6)
* ASIND: ASIND. (line 6)
* ASINH: ASINH. (line 6)
* ASSOCIATED: ASSOCIATED. (line 6)
* association status: ASSOCIATED. (line 6)
* association status, C pointer: C_ASSOCIATED. (line 6)
* asynchronous I/O: Asynchronous I/O. (line 6)
* ATAN: ATAN. (line 6)
* ATAN2: ATAN2. (line 6)
* ATAN2D: ATAN2D. (line 6)
* ATAND: ATAND. (line 6)
* ATANH: ATANH. (line 6)
* Atomic subroutine, add: ATOMIC_ADD. (line 6)
* Atomic subroutine, ADD with fetch: ATOMIC_FETCH_ADD. (line 6)
* Atomic subroutine, AND: ATOMIC_AND. (line 6)
* Atomic subroutine, AND with fetch: ATOMIC_FETCH_AND. (line 6)
* Atomic subroutine, compare and swap: ATOMIC_CAS. (line 6)
* Atomic subroutine, define: ATOMIC_DEFINE. (line 6)
* Atomic subroutine, OR: ATOMIC_OR. (line 6)
* Atomic subroutine, OR with fetch: ATOMIC_FETCH_OR. (line 6)
* Atomic subroutine, reference: ATOMIC_REF. (line 6)
* Atomic subroutine, XOR: ATOMIC_XOR. (line 6)
* Atomic subroutine, XOR with fetch: ATOMIC_FETCH_XOR. (line 6)
* ATOMIC_ADD: ATOMIC_ADD. (line 6)
* ATOMIC_AND: ATOMIC_AND. (line 6)
* ATOMIC_DEFINE <1>: ATOMIC_DEFINE. (line 6)
* ATOMIC_DEFINE: ATOMIC_CAS. (line 6)
* ATOMIC_FETCH_ADD: ATOMIC_FETCH_ADD. (line 6)
* ATOMIC_FETCH_AND: ATOMIC_FETCH_AND. (line 6)
* ATOMIC_FETCH_OR: ATOMIC_FETCH_OR. (line 6)
* ATOMIC_FETCH_XOR: ATOMIC_FETCH_XOR. (line 6)
* ATOMIC_OR: ATOMIC_OR. (line 6)
* ATOMIC_REF: ATOMIC_REF. (line 6)
* ATOMIC_XOR: ATOMIC_XOR. (line 6)
* Authors: Contributors. (line 6)
* AUTOMATIC: AUTOMATIC and STATIC attributes.
(line 6)
* BABS: ABS. (line 6)
* backslash: Fortran Dialect Options.
(line 79)
* BACKSPACE: Read/Write after EOF marker.
(line 6)
* backtrace: BACKTRACE. (line 6)
* BACKTRACE: BACKTRACE. (line 6)
* backtrace: Debugging Options. (line 87)
* base 10 logarithm function: LOG10. (line 6)
* BBCLR: IBCLR. (line 6)
* BBITS: IBITS. (line 6)
* BBSET: IBSET. (line 6)
* BBTEST: BTEST. (line 6)
* BESJ0: BESSEL_J0. (line 6)
* BESJ1: BESSEL_J1. (line 6)
* BESJN: BESSEL_JN. (line 6)
* Bessel function, first kind <1>: BESSEL_JN. (line 6)
* Bessel function, first kind <2>: BESSEL_J1. (line 6)
* Bessel function, first kind: BESSEL_J0. (line 6)
* Bessel function, second kind <1>: BESSEL_YN. (line 6)
* Bessel function, second kind <2>: BESSEL_Y1. (line 6)
* Bessel function, second kind: BESSEL_Y0. (line 6)
* BESSEL_J0: BESSEL_J0. (line 6)
* BESSEL_J1: BESSEL_J1. (line 6)
* BESSEL_JN: BESSEL_JN. (line 6)
* BESSEL_Y0: BESSEL_Y0. (line 6)
* BESSEL_Y1: BESSEL_Y1. (line 6)
* BESSEL_YN: BESSEL_YN. (line 6)
* BESY0: BESSEL_Y0. (line 6)
* BESY1: BESSEL_Y1. (line 6)
* BESYN: BESSEL_YN. (line 6)
* BGE: BGE. (line 6)
* BGT: BGT. (line 6)
* BIAND: IAND. (line 6)
* BIEOR: IEOR. (line 6)
* binary representation <1>: POPPAR. (line 6)
* binary representation: POPCNT. (line 6)
* BIOR: IOR. (line 6)
* BIT_SIZE: BIT_SIZE. (line 6)
* BITEST: BTEST. (line 6)
* bits set: POPCNT. (line 6)
* bits, AND of array elements: IALL. (line 6)
* bits, clear: IBCLR. (line 6)
* bits, extract: IBITS. (line 6)
* bits, get: IBITS. (line 6)
* bits, merge: MERGE_BITS. (line 6)
* bits, move <1>: TRANSFER. (line 6)
* bits, move: MVBITS. (line 6)
* bits, negate: NOT. (line 6)
* bits, number of: BIT_SIZE. (line 6)
* bits, OR of array elements: IANY. (line 6)
* bits, set: IBSET. (line 6)
* bits, shift: ISHFT. (line 6)
* bits, shift circular: ISHFTC. (line 6)
* bits, shift left <1>: SHIFTL. (line 6)
* bits, shift left: LSHIFT. (line 6)
* bits, shift right <1>: SHIFTR. (line 6)
* bits, shift right <2>: SHIFTA. (line 6)
* bits, shift right: RSHIFT. (line 6)
* bits, testing: BTEST. (line 6)
* bits, unset: IBCLR. (line 6)
* bits, XOR of array elements: IPARITY. (line 6)
* bitwise comparison <1>: BLT. (line 6)
* bitwise comparison <2>: BLE. (line 6)
* bitwise comparison <3>: BGT. (line 6)
* bitwise comparison: BGE. (line 6)
* bitwise logical and <1>: IAND. (line 6)
* bitwise logical and: AND. (line 6)
* bitwise logical exclusive or <1>: XOR. (line 6)
* bitwise logical exclusive or: IEOR. (line 6)
* bitwise logical not: NOT. (line 6)
* bitwise logical or <1>: OR. (line 6)
* bitwise logical or: IOR. (line 6)
* BJTEST: BTEST. (line 6)
* BKTEST: BTEST. (line 6)
* BLE: BLE. (line 6)
* BLT: BLT. (line 6)
* BMOD: MOD. (line 6)
* BMVBITS: MVBITS. (line 6)
* BNOT: NOT. (line 6)
* bounds checking: Code Gen Options. (line 146)
* BOZ literal constants: BOZ literal constants.
(line 6)
* BSHFT: ISHFT. (line 6)
* BSHFTC: ISHFTC. (line 6)
* BTEST: BTEST. (line 6)
* C_ASSOCIATED: C_ASSOCIATED. (line 6)
* C_F_POINTER: C_F_POINTER. (line 6)
* C_F_PROCPOINTER: C_F_PROCPOINTER. (line 6)
* C_FUNLOC: C_FUNLOC. (line 6)
* C_LOC: C_LOC. (line 6)
* C_SIZEOF: C_SIZEOF. (line 6)
* CABS: ABS. (line 6)
* calling convention: Code Gen Options. (line 28)
* CARRIAGECONTROL: Extended I/O specifiers.
(line 6)
* CCOS: COS. (line 6)
* CCOSD: COSD. (line 6)
* CDABS: ABS. (line 6)
* CDCOS: COS. (line 6)
* CDCOSD: COSD. (line 6)
* CDEXP: EXP. (line 6)
* CDLOG: LOG. (line 6)
* CDSIN: SIN. (line 6)
* CDSIND: SIND. (line 6)
* CDSQRT: SQRT. (line 6)
* ceiling: CEILING. (line 6)
* CEILING: CEILING. (line 6)
* ceiling: ANINT. (line 6)
* CEXP: EXP. (line 6)
* CHAR: CHAR. (line 6)
* character kind: SELECTED_CHAR_KIND. (line 6)
* character set: Fortran Dialect Options.
(line 73)
* CHDIR: CHDIR. (line 6)
* checking array temporaries: Code Gen Options. (line 146)
* checking subscripts: Code Gen Options. (line 146)
* CHMOD: CHMOD. (line 6)
* clock ticks <1>: SYSTEM_CLOCK. (line 6)
* clock ticks <2>: MCLOCK8. (line 6)
* clock ticks: MCLOCK. (line 6)
* CLOG: LOG. (line 6)
* CMPLX: CMPLX. (line 6)
* CO_BROADCAST: CO_BROADCAST. (line 6)
* CO_MAX: CO_MAX. (line 6)
* CO_MIN: CO_MIN. (line 6)
* CO_REDUCE: CO_REDUCE. (line 6)
* CO_SUM: CO_SUM. (line 6)
* Coarray, _gfortran_caf_atomic_cas: _gfortran_caf_atomic_cas.
(line 6)
* Coarray, _gfortran_caf_atomic_define: _gfortran_caf_atomic_define.
(line 6)
* Coarray, _gfortran_caf_atomic_op: _gfortran_caf_atomic_op.
(line 6)
* Coarray, _gfortran_caf_atomic_ref: _gfortran_caf_atomic_ref.
(line 6)
* Coarray, _gfortran_caf_co_broadcast: _gfortran_caf_co_broadcast.
(line 6)
* Coarray, _gfortran_caf_co_max: _gfortran_caf_co_max.
(line 6)
* Coarray, _gfortran_caf_co_min: _gfortran_caf_co_min.
(line 6)
* Coarray, _gfortran_caf_co_reduce: _gfortran_caf_co_reduce.
(line 6)
* Coarray, _gfortran_caf_co_sum: _gfortran_caf_co_sum.
(line 6)
* Coarray, _gfortran_caf_deregister: _gfortran_caf_deregister.
(line 6)
* Coarray, _gfortran_caf_error_stop: _gfortran_caf_error_stop.
(line 6)
* Coarray, _gfortran_caf_error_stop_str: _gfortran_caf_error_stop_str.
(line 6)
* Coarray, _gfortran_caf_event_post: _gfortran_caf_event_post.
(line 6)
* Coarray, _gfortran_caf_event_query: _gfortran_caf_event_query.
(line 6)
* Coarray, _gfortran_caf_event_wait: _gfortran_caf_event_wait.
(line 6)
* Coarray, _gfortran_caf_fail_image: _gfortran_caf_fail_image.
(line 6)
* Coarray, _gfortran_caf_failed_images: _gfortran_caf_failed_images.
(line 6)
* Coarray, _gfortran_caf_finish: _gfortran_caf_finish.
(line 6)
* Coarray, _gfortran_caf_get: _gfortran_caf_get. (line 6)
* Coarray, _gfortran_caf_get_by_ref: _gfortran_caf_get_by_ref.
(line 6)
* Coarray, _gfortran_caf_image_status: _gfortran_caf_image_status.
(line 6)
* Coarray, _gfortran_caf_init: _gfortran_caf_init. (line 6)
* Coarray, _gfortran_caf_is_present: _gfortran_caf_is_present.
(line 6)
* Coarray, _gfortran_caf_lock: _gfortran_caf_lock. (line 6)
* Coarray, _gfortran_caf_num_images: _gfortran_caf_num_images.
(line 6)
* Coarray, _gfortran_caf_register: _gfortran_caf_register.
(line 6)
* Coarray, _gfortran_caf_send: _gfortran_caf_send. (line 6)
* Coarray, _gfortran_caf_send_by_ref: _gfortran_caf_send_by_ref.
(line 6)
* Coarray, _gfortran_caf_sendget: _gfortran_caf_sendget.
(line 6)
* Coarray, _gfortran_caf_sendget_by_ref: _gfortran_caf_sendget_by_ref.
(line 6)
* Coarray, _gfortran_caf_stopped_images: _gfortran_caf_stopped_images.
(line 6)
* Coarray, _gfortran_caf_sync_all: _gfortran_caf_sync_all.
(line 6)
* Coarray, _gfortran_caf_sync_images: _gfortran_caf_sync_images.
(line 6)
* Coarray, _gfortran_caf_sync_memory: _gfortran_caf_sync_memory.
(line 6)
* Coarray, _gfortran_caf_this_image: _gfortran_caf_this_image.
(line 6)
* Coarray, _gfortran_caf_unlock: _gfortran_caf_unlock.
(line 6)
* coarray, IMAGE_INDEX: IMAGE_INDEX. (line 6)
* coarray, lower bound: LCOBOUND. (line 6)
* coarray, NUM_IMAGES: NUM_IMAGES. (line 6)
* coarray, THIS_IMAGE: THIS_IMAGE. (line 6)
* coarray, upper bound: UCOBOUND. (line 6)
* Coarrays: Coarray Programming. (line 6)
* coarrays: Code Gen Options. (line 132)
* code generation, conventions: Code Gen Options. (line 6)
* collating sequence, ASCII <1>: IACHAR. (line 6)
* collating sequence, ASCII: ACHAR. (line 6)
* Collectives, generic reduction: CO_REDUCE. (line 6)
* Collectives, maximal value: CO_MAX. (line 6)
* Collectives, minimal value: CO_MIN. (line 6)
* Collectives, sum of values: CO_SUM. (line 6)
* Collectives, value broadcasting: CO_BROADCAST. (line 6)
* command line: EXECUTE_COMMAND_LINE.
(line 6)
* command options: Invoking GNU Fortran.
(line 6)
* command-line arguments <1>: IARGC. (line 6)
* command-line arguments <2>: GET_COMMAND_ARGUMENT.
(line 6)
* command-line arguments <3>: GET_COMMAND. (line 6)
* command-line arguments <4>: GETARG. (line 6)
* command-line arguments: COMMAND_ARGUMENT_COUNT.
(line 6)
* command-line arguments, number of <1>: IARGC. (line 6)
* command-line arguments, number of: COMMAND_ARGUMENT_COUNT.
(line 6)
* COMMAND_ARGUMENT_COUNT: COMMAND_ARGUMENT_COUNT.
(line 6)
* COMMON: Volatile COMMON blocks.
(line 6)
* compiler flags inquiry function: COMPILER_OPTIONS. (line 6)
* compiler, name and version: COMPILER_VERSION. (line 6)
* COMPILER_OPTIONS: COMPILER_OPTIONS. (line 6)
* COMPILER_VERSION: COMPILER_VERSION. (line 6)
* COMPLEX: COMPLEX. (line 6)
* complex conjugate: CONJG. (line 6)
* Complex function: Alternate complex function syntax.
(line 6)
* complex numbers, conversion to <1>: DCMPLX. (line 6)
* complex numbers, conversion to <2>: COMPLEX. (line 6)
* complex numbers, conversion to: CMPLX. (line 6)
* complex numbers, imaginary part: AIMAG. (line 6)
* complex numbers, real part <1>: REAL. (line 6)
* complex numbers, real part: DREAL. (line 6)
* Conditional compilation: Preprocessing and conditional compilation.
(line 6)
* CONJG: CONJG. (line 6)
* consistency, durability: Data consistency and durability.
(line 6)
* Contributing: Contributing. (line 6)
* Contributors: Contributors. (line 6)
* conversion: Error and Warning Options.
(line 122)
* conversion, to character: CHAR. (line 6)
* conversion, to complex <1>: DCMPLX. (line 6)
* conversion, to complex <2>: COMPLEX. (line 6)
* conversion, to complex: CMPLX. (line 6)
* conversion, to integer <1>: LONG. (line 6)
* conversion, to integer <2>: INT8. (line 6)
* conversion, to integer <3>: INT2. (line 6)
* conversion, to integer <4>: INT. (line 6)
* conversion, to integer <5>: ICHAR. (line 6)
* conversion, to integer <6>: IACHAR. (line 6)
* conversion, to integer: Implicitly convert LOGICAL and INTEGER values.
(line 6)
* conversion, to logical <1>: LOGICAL. (line 6)
* conversion, to logical: Implicitly convert LOGICAL and INTEGER values.
(line 6)
* conversion, to real <1>: REAL. (line 6)
* conversion, to real: DBLE. (line 6)
* conversion, to string: CTIME. (line 6)
* CONVERT specifier: CONVERT specifier. (line 6)
* core, dump: ABORT. (line 6)
* COS: COS. (line 6)
* COSD: COSD. (line 6)
* COSH: COSH. (line 6)
* cosine: COS. (line 6)
* cosine, degrees: COSD. (line 6)
* cosine, hyperbolic: COSH. (line 6)
* cosine, hyperbolic, inverse: ACOSH. (line 6)
* cosine, inverse: ACOS. (line 6)
* cosine, inverse, degrees: ACOSD. (line 6)
* COTAN: COTAN. (line 6)
* COTAND: COTAND. (line 6)
* cotangent: COTAN. (line 6)
* cotangent, degrees: COTAND. (line 6)
* COUNT: COUNT. (line 6)
* CPP <1>: Preprocessing Options.
(line 6)
* CPP: Preprocessing and conditional compilation.
(line 6)
* CPU_TIME: CPU_TIME. (line 6)
* Credits: Contributors. (line 6)
* CSHIFT: CSHIFT. (line 6)
* CSIN: SIN. (line 6)
* CSIND: SIND. (line 6)
* CSQRT: SQRT. (line 6)
* CTIME: CTIME. (line 6)
* current date <1>: IDATE. (line 6)
* current date <2>: FDATE. (line 6)
* current date: DATE_AND_TIME. (line 6)
* current time <1>: TIME8. (line 6)
* current time <2>: TIME. (line 6)
* current time <3>: ITIME. (line 6)
* current time <4>: FDATE. (line 6)
* current time: DATE_AND_TIME. (line 6)
* DABS: ABS. (line 6)
* DACOS: ACOS. (line 6)
* DACOSD: ACOSD. (line 6)
* DACOSH: ACOSH. (line 6)
* DASIN: ASIN. (line 6)
* DASIND: ASIND. (line 6)
* DASINH: ASINH. (line 6)
* DATAN: ATAN. (line 6)
* DATAN2: ATAN2. (line 6)
* DATAN2D: ATAN2D. (line 6)
* DATAND: ATAND. (line 6)
* DATANH: ATANH. (line 6)
* date, current <1>: IDATE. (line 6)
* date, current <2>: FDATE. (line 6)
* date, current: DATE_AND_TIME. (line 6)
* DATE_AND_TIME: DATE_AND_TIME. (line 6)
* DBESJ0: BESSEL_J0. (line 6)
* DBESJ1: BESSEL_J1. (line 6)
* DBESJN: BESSEL_JN. (line 6)
* DBESY0: BESSEL_Y0. (line 6)
* DBESY1: BESSEL_Y1. (line 6)
* DBESYN: BESSEL_YN. (line 6)
* DBLE: DBLE. (line 6)
* DCMPLX: DCMPLX. (line 6)
* DCONJG: CONJG. (line 6)
* DCOS: COS. (line 6)
* DCOSD: COSD. (line 6)
* DCOSH: COSH. (line 6)
* DCOTAN: COTAN. (line 6)
* DCOTAND: COTAND. (line 6)
* DDIM: DIM. (line 6)
* debugging information options: Debugging Options. (line 6)
* debugging, preprocessor: Preprocessing Options.
(line 26)
* DECODE: ENCODE and DECODE statements.
(line 6)
* delayed execution <1>: SLEEP. (line 6)
* delayed execution: ALARM. (line 6)
* DEXP: EXP. (line 6)
* DFLOAT: REAL. (line 6)
* DGAMMA: GAMMA. (line 6)
* dialect options: Fortran Dialect Options.
(line 6)
* DIGITS: DIGITS. (line 6)
* DIM: DIM. (line 6)
* DIMAG: AIMAG. (line 6)
* DINT: AINT. (line 6)
* directive, INCLUDE: Directory Options. (line 6)
* directory, options: Directory Options. (line 6)
* directory, search paths for inclusion: Directory Options. (line 14)
* division, modulo: MODULO. (line 6)
* division, remainder: MOD. (line 6)
* DLGAMA: LOG_GAMMA. (line 6)
* DLOG: LOG. (line 6)
* DLOG10: LOG10. (line 6)
* DMAX1: MAX. (line 6)
* DMIN1: MIN. (line 6)
* DMOD: MOD. (line 6)
* DNINT: ANINT. (line 6)
* dot product: DOT_PRODUCT. (line 6)
* DOT_PRODUCT: DOT_PRODUCT. (line 6)
* DPROD: DPROD. (line 6)
* DREAL: DREAL. (line 6)
* DSHIFTL: DSHIFTL. (line 6)
* DSHIFTR: DSHIFTR. (line 6)
* DSIGN: SIGN. (line 6)
* DSIN: SIN. (line 6)
* DSIND: SIND. (line 6)
* DSINH: SINH. (line 6)
* DSQRT: SQRT. (line 6)
* DTAN: TAN. (line 6)
* DTAND: TAND. (line 6)
* DTANH: TANH. (line 6)
* DTIME: DTIME. (line 6)
* dummy argument, unused: Error and Warning Options.
(line 215)
* elapsed time <1>: SECOND. (line 6)
* elapsed time <2>: SECNDS. (line 6)
* elapsed time: DTIME. (line 6)
* Elimination of functions with identical argument lists: Code Gen Options.
(line 411)
* ENCODE: ENCODE and DECODE statements.
(line 6)
* ENUM statement: Fortran 2003 status. (line 92)
* ENUMERATOR statement: Fortran 2003 status. (line 92)
* environment variable <1>: GET_ENVIRONMENT_VARIABLE.
(line 6)
* environment variable <2>: GETENV. (line 6)
* environment variable <3>: Runtime. (line 6)
* environment variable: Environment Variables.
(line 6)
* EOF: Read/Write after EOF marker.
(line 6)
* EOSHIFT: EOSHIFT. (line 6)
* EPSILON: EPSILON. (line 6)
* ERF: ERF. (line 6)
* ERFC: ERFC. (line 6)
* ERFC_SCALED: ERFC_SCALED. (line 6)
* error function: ERF. (line 6)
* error function, complementary: ERFC. (line 6)
* error function, complementary, exponentially-scaled: ERFC_SCALED.
(line 6)
* errors, limiting: Error and Warning Options.
(line 27)
* escape characters: Fortran Dialect Options.
(line 79)
* ETIME: ETIME. (line 6)
* Euclidean distance: HYPOT. (line 6)
* Euclidean vector norm: NORM2. (line 6)
* EVENT_QUERY: EVENT_QUERY. (line 6)
* Events, EVENT_QUERY: EVENT_QUERY. (line 6)
* EXECUTE_COMMAND_LINE: EXECUTE_COMMAND_LINE.
(line 6)
* EXIT: EXIT. (line 6)
* EXP: EXP. (line 6)
* EXPONENT: EXPONENT. (line 6)
* exponent: Default exponents. (line 6)
* exponential function: EXP. (line 6)
* exponential function, inverse <1>: LOG10. (line 6)
* exponential function, inverse: LOG. (line 6)
* expression size <1>: SIZEOF. (line 6)
* expression size: C_SIZEOF. (line 6)
* EXTENDS_TYPE_OF: EXTENDS_TYPE_OF. (line 6)
* extensions: Extensions. (line 6)
* extensions, implemented: Extensions implemented in GNU Fortran.
(line 6)
* extensions, not implemented: Extensions not implemented in GNU Fortran.
(line 6)
* extra warnings: Error and Warning Options.
(line 130)
* f2c calling convention: Code Gen Options. (line 28)
* Factorial function: GAMMA. (line 6)
* FDATE: FDATE. (line 6)
* FDL, GNU Free Documentation License: GNU Free Documentation License.
(line 6)
* FGET: FGET. (line 6)
* FGETC: FGETC. (line 6)
* file format, fixed: Fortran Dialect Options.
(line 11)
* file format, free: Fortran Dialect Options.
(line 11)
* file operation, file number: FNUM. (line 6)
* file operation, flush: FLUSH. (line 6)
* file operation, position <1>: FTELL. (line 6)
* file operation, position: FSEEK. (line 6)
* file operation, read character <1>: FGETC. (line 6)
* file operation, read character: FGET. (line 6)
* file operation, seek: FSEEK. (line 6)
* file operation, write character <1>: FPUTC. (line 6)
* file operation, write character: FPUT. (line 6)
* file system, access mode: ACCESS. (line 6)
* file system, change access mode: CHMOD. (line 6)
* file system, create link <1>: SYMLNK. (line 6)
* file system, create link: LINK. (line 6)
* file system, file creation mask: UMASK. (line 6)
* file system, file status <1>: STAT. (line 6)
* file system, file status <2>: LSTAT. (line 6)
* file system, file status: FSTAT. (line 6)
* file system, hard link: LINK. (line 6)
* file system, remove file: UNLINK. (line 6)
* file system, rename file: RENAME. (line 6)
* file system, soft link: SYMLNK. (line 6)
* file, symbolic link: File operations on symbolic links.
(line 6)
* file, unformatted sequential: File format of unformatted sequential files.
(line 6)
* findloc: FINDLOC. (line 6)
* FINDLOC: FINDLOC. (line 6)
* flags inquiry function: COMPILER_OPTIONS. (line 6)
* FLOAT: REAL. (line 6)
* FLOATI: REAL. (line 6)
* floating point, exponent: EXPONENT. (line 6)
* floating point, fraction: FRACTION. (line 6)
* floating point, nearest different: NEAREST. (line 6)
* floating point, relative spacing <1>: SPACING. (line 6)
* floating point, relative spacing: RRSPACING. (line 6)
* floating point, scale: SCALE. (line 6)
* floating point, set exponent: SET_EXPONENT. (line 6)
* FLOATJ: REAL. (line 6)
* FLOATK: REAL. (line 6)
* floor: FLOOR. (line 6)
* FLOOR: FLOOR. (line 6)
* floor: AINT. (line 6)
* FLUSH: FLUSH. (line 6)
* FLUSH statement: Fortran 2003 status. (line 88)
* FNUM: FNUM. (line 6)
* form feed whitespace: Form feed as whitespace.
(line 6)
* FORMAT: Variable FORMAT expressions.
(line 6)
* Fortran 77: GNU Fortran and G77. (line 6)
* FPP: Preprocessing and conditional compilation.
(line 6)
* FPUT: FPUT. (line 6)
* FPUTC: FPUTC. (line 6)
* FRACTION: FRACTION. (line 6)
* FREE: FREE. (line 6)
* Front-end optimization: Code Gen Options. (line 419)
* FSEEK: FSEEK. (line 6)
* FSTAT: FSTAT. (line 6)
* FTELL: FTELL. (line 6)
* function elimination: Error and Warning Options.
(line 232)
* g77: GNU Fortran and G77. (line 6)
* g77 calling convention: Code Gen Options. (line 28)
* GAMMA: GAMMA. (line 6)
* Gamma function: GAMMA. (line 6)
* Gamma function, logarithm of: LOG_GAMMA. (line 6)
* GCC: GNU Fortran and GCC. (line 6)
* Generating C prototypes from external procedures: Interoperability Options.
(line 25)
* Generating C prototypes from Fortran BIND(C) enteties: Interoperability Options.
(line 7)
* GERROR: GERROR. (line 6)
* GET_COMMAND: GET_COMMAND. (line 6)
* GET_COMMAND_ARGUMENT: GET_COMMAND_ARGUMENT.
(line 6)
* GET_ENVIRONMENT_VARIABLE: GET_ENVIRONMENT_VARIABLE.
(line 6)
* GETARG: GETARG. (line 6)
* GETCWD: GETCWD. (line 6)
* GETENV: GETENV. (line 6)
* GETGID: GETGID. (line 6)
* GETLOG: GETLOG. (line 6)
* GETPID: GETPID. (line 6)
* GETUID: GETUID. (line 6)
* GMTIME: GMTIME. (line 6)
* GNU Compiler Collection: GNU Fortran and GCC. (line 6)
* GNU Fortran command options: Invoking GNU Fortran.
(line 6)
* Hollerith constants: Hollerith constants support.
(line 6)
* HOSTNM: HOSTNM. (line 6)
* HUGE: HUGE. (line 6)
* hyperbolic cosine: COSH. (line 6)
* hyperbolic function, cosine: COSH. (line 6)
* hyperbolic function, cosine, inverse: ACOSH. (line 6)
* hyperbolic function, sine: SINH. (line 6)
* hyperbolic function, sine, inverse: ASINH. (line 6)
* hyperbolic function, tangent: TANH. (line 6)
* hyperbolic function, tangent, inverse: ATANH. (line 6)
* hyperbolic sine: SINH. (line 6)
* hyperbolic tangent: TANH. (line 6)
* HYPOT: HYPOT. (line 6)
* I/O item lists: I/O item lists. (line 6)
* I/O specifiers: Extended I/O specifiers.
(line 6)
* IABS: ABS. (line 6)
* IACHAR: IACHAR. (line 6)
* IALL: IALL. (line 6)
* IAND: IAND. (line 6)
* IANY: IANY. (line 6)
* IARGC: IARGC. (line 6)
* IBCLR: IBCLR. (line 6)
* IBITS: IBITS. (line 6)
* IBSET: IBSET. (line 6)
* ICHAR: ICHAR. (line 6)
* IDATE: IDATE. (line 6)
* IDIM: DIM. (line 6)
* IDINT: INT. (line 6)
* IDNINT: NINT. (line 6)
* IEEE, ISNAN: ISNAN. (line 6)
* IEOR: IEOR. (line 6)
* IERRNO: IERRNO. (line 6)
* IFIX: INT. (line 6)
* IIABS: ABS. (line 6)
* IIAND: IAND. (line 6)
* IIBCLR: IBCLR. (line 6)
* IIBITS: IBITS. (line 6)
* IIBSET: IBSET. (line 6)
* IIEOR: IEOR. (line 6)
* IIOR: IOR. (line 6)
* IISHFT: ISHFT. (line 6)
* IISHFTC: ISHFTC. (line 6)
* IMAG: AIMAG. (line 6)
* IMAGE_INDEX: IMAGE_INDEX. (line 6)
* images, cosubscript to image index conversion: IMAGE_INDEX. (line 6)
* images, index of this image: THIS_IMAGE. (line 6)
* images, number of: NUM_IMAGES. (line 6)
* IMAGPART: AIMAG. (line 6)
* IMOD: MOD. (line 6)
* IMPORT statement: Fortran 2003 status. (line 121)
* IMVBITS: MVBITS. (line 6)
* INCLUDE directive: Directory Options. (line 6)
* inclusion, directory search paths for: Directory Options. (line 14)
* INDEX: INDEX intrinsic. (line 6)
* INOT: NOT. (line 6)
* input/output, asynchronous: Asynchronous I/O. (line 6)
* INT: INT. (line 6)
* INT2: INT2. (line 6)
* INT8: INT8. (line 6)
* integer kind: SELECTED_INT_KIND. (line 6)
* Interoperability: Mixed-Language Programming.
(line 6)
* intrinsic: Error and Warning Options.
(line 204)
* intrinsic Modules: Intrinsic Modules. (line 6)
* intrinsic procedures: Intrinsic Procedures.
(line 6)
* intrinsics, integer: Type variants for integer intrinsics.
(line 6)
* intrinsics, math: Extended math intrinsics.
(line 6)
* intrinsics, trigonometric functions: Extended math intrinsics.
(line 6)
* Introduction: Top. (line 6)
* inverse hyperbolic cosine: ACOSH. (line 6)
* inverse hyperbolic sine: ASINH. (line 6)
* inverse hyperbolic tangent: ATANH. (line 6)
* IOMSG= specifier: Fortran 2003 status. (line 90)
* IOR: IOR. (line 6)
* IOSTAT, end of file: IS_IOSTAT_END. (line 6)
* IOSTAT, end of record: IS_IOSTAT_EOR. (line 6)
* IPARITY: IPARITY. (line 6)
* IRAND: IRAND. (line 6)
* IS_IOSTAT_END: IS_IOSTAT_END. (line 6)
* IS_IOSTAT_EOR <1>: IS_IOSTAT_EOR. (line 6)
* IS_IOSTAT_EOR: IS_CONTIGUOUS. (line 6)
* ISATTY: ISATTY. (line 6)
* ISHFT: ISHFT. (line 6)
* ISHFTC: ISHFTC. (line 6)
* ISIGN: SIGN. (line 6)
* ISNAN: ISNAN. (line 6)
* ISO_FORTRAN_ENV statement: Fortran 2003 status. (line 129)
* ITIME: ITIME. (line 6)
* JIABS: ABS. (line 6)
* JIAND: IAND. (line 6)
* JIBCLR: IBCLR. (line 6)
* JIBITS: IBITS. (line 6)
* JIBSET: IBSET. (line 6)
* JIEOR: IEOR. (line 6)
* JIOR: IOR. (line 6)
* JISHFT: ISHFT. (line 6)
* JISHFTC: ISHFTC. (line 6)
* JMOD: MOD. (line 6)
* JMVBITS: MVBITS. (line 6)
* JNOT: NOT. (line 6)
* KIABS: ABS. (line 6)
* KIAND: IAND. (line 6)
* KIBCLR: IBCLR. (line 6)
* KIBITS: IBITS. (line 6)
* KIBSET: IBSET. (line 6)
* KIEOR: IEOR. (line 6)
* KILL: KILL. (line 6)
* kind: KIND. (line 6)
* KIND: KIND. (line 6)
* kind: KIND Type Parameters.
(line 6)
* kind, character: SELECTED_CHAR_KIND. (line 6)
* kind, integer: SELECTED_INT_KIND. (line 6)
* kind, old-style: Old-style kind specifications.
(line 6)
* kind, real: SELECTED_REAL_KIND. (line 6)
* KIOR: IOR. (line 6)
* KISHFT: ISHFT. (line 6)
* KISHFTC: ISHFTC. (line 6)
* KMOD: MOD. (line 6)
* KMVBITS: MVBITS. (line 6)
* KNOT: NOT. (line 6)
* L2 vector norm: NORM2. (line 6)
* language, dialect options: Fortran Dialect Options.
(line 6)
* LBOUND: LBOUND. (line 6)
* LCOBOUND: LCOBOUND. (line 6)
* LEADZ: LEADZ. (line 6)
* left shift, combined: DSHIFTL. (line 6)
* LEN: LEN. (line 6)
* LEN_TRIM: LEN_TRIM. (line 6)
* lexical comparison of strings <1>: LLT. (line 6)
* lexical comparison of strings <2>: LLE. (line 6)
* lexical comparison of strings <3>: LGT. (line 6)
* lexical comparison of strings: LGE. (line 6)
* LGAMMA: LOG_GAMMA. (line 6)
* LGE: LGE. (line 6)
* LGT: LGT. (line 6)
* libf2c calling convention: Code Gen Options. (line 28)
* libgfortran initialization, set_args: _gfortran_set_args. (line 6)
* libgfortran initialization, set_convert: _gfortran_set_convert.
(line 6)
* libgfortran initialization, set_fpe: _gfortran_set_fpe. (line 6)
* libgfortran initialization, set_max_subrecord_length: _gfortran_set_max_subrecord_length.
(line 6)
* libgfortran initialization, set_options: _gfortran_set_options.
(line 6)
* libgfortran initialization, set_record_marker: _gfortran_set_record_marker.
(line 6)
* limits, largest number: HUGE. (line 6)
* limits, smallest number: TINY. (line 6)
* LINK: LINK. (line 6)
* linking, static: Link Options. (line 6)
* LLE: LLE. (line 6)
* LLT: LLT. (line 6)
* LNBLNK: LNBLNK. (line 6)
* LOC <1>: LOC. (line 6)
* LOC: %LOC as an rvalue. (line 6)
* location of a variable in memory: LOC. (line 6)
* LOG: LOG. (line 6)
* LOG10: LOG10. (line 6)
* LOG_GAMMA: LOG_GAMMA. (line 6)
* logarithm function: LOG. (line 6)
* logarithm function with base 10: LOG10. (line 6)
* logarithm function, inverse: EXP. (line 6)
* LOGICAL: LOGICAL. (line 6)
* logical and, bitwise <1>: IAND. (line 6)
* logical and, bitwise: AND. (line 6)
* logical exclusive or, bitwise <1>: XOR. (line 6)
* logical exclusive or, bitwise: IEOR. (line 6)
* logical not, bitwise: NOT. (line 6)
* logical or, bitwise <1>: OR. (line 6)
* logical or, bitwise: IOR. (line 6)
* logical, bitwise: Bitwise logical operators.
(line 6)
* logical, variable representation: Internal representation of LOGICAL variables.
(line 6)
* login name: GETLOG. (line 6)
* LONG: LONG. (line 6)
* loop interchange, Fortran: Code Gen Options. (line 436)
* loop interchange, warning: Error and Warning Options.
(line 135)
* LSHIFT: LSHIFT. (line 6)
* LSTAT: LSTAT. (line 6)
* LTIME: LTIME. (line 6)
* MALLOC: MALLOC. (line 6)
* MAP: UNION and MAP. (line 6)
* mask, left justified: MASKL. (line 6)
* mask, right justified: MASKR. (line 6)
* MASKL: MASKL. (line 6)
* MASKR: MASKR. (line 6)
* MATMUL: MATMUL. (line 6)
* matrix multiplication: MATMUL. (line 6)
* matrix, transpose: TRANSPOSE. (line 6)
* MAX: MAX. (line 6)
* MAX, MIN, NaN: MAX and MIN intrinsics with REAL NaN arguments.
(line 6)
* MAX0: MAX. (line 6)
* MAX1: MAX. (line 6)
* MAXEXPONENT: MAXEXPONENT. (line 6)
* maximum value <1>: MAXVAL. (line 6)
* maximum value: MAX. (line 6)
* MAXLOC: MAXLOC. (line 6)
* MAXVAL: MAXVAL. (line 6)
* MCLOCK: MCLOCK. (line 6)
* MCLOCK8: MCLOCK8. (line 6)
* memory checking: Code Gen Options. (line 146)
* MERGE: MERGE. (line 6)
* MERGE_BITS: MERGE_BITS. (line 6)
* messages, error: Error and Warning Options.
(line 6)
* messages, warning: Error and Warning Options.
(line 6)
* MIN: MIN. (line 6)
* MIN0: MIN. (line 6)
* MIN1: MIN. (line 6)
* MINEXPONENT: MINEXPONENT. (line 6)
* minimum value <1>: MINVAL. (line 6)
* minimum value: MIN. (line 6)
* MINLOC: MINLOC. (line 6)
* MINVAL: MINVAL. (line 6)
* Mixed-language programming: Mixed-Language Programming.
(line 6)
* MOD: MOD. (line 6)
* model representation, base: RADIX. (line 6)
* model representation, epsilon: EPSILON. (line 6)
* model representation, largest number: HUGE. (line 6)
* model representation, maximum exponent: MAXEXPONENT. (line 6)
* model representation, minimum exponent: MINEXPONENT. (line 6)
* model representation, precision: PRECISION. (line 6)
* model representation, radix: RADIX. (line 6)
* model representation, range: RANGE. (line 6)
* model representation, significant digits: DIGITS. (line 6)
* model representation, smallest number: TINY. (line 6)
* module entities: Fortran Dialect Options.
(line 91)
* module search path: Directory Options. (line 14)
* modulo: MODULO. (line 6)
* MODULO: MODULO. (line 6)
* MOVE_ALLOC: MOVE_ALLOC. (line 6)
* moving allocation: MOVE_ALLOC. (line 6)
* multiply array elements: PRODUCT. (line 6)
* MVBITS: MVBITS. (line 6)
* NAME: OPEN( ... NAME=). (line 6)
* Namelist: Extensions to namelist.
(line 6)
* natural logarithm function: LOG. (line 6)
* NEAREST: NEAREST. (line 6)
* NEW_LINE: NEW_LINE. (line 6)
* newline: NEW_LINE. (line 6)
* NINT: NINT. (line 6)
* norm, Euclidean: NORM2. (line 6)
* NORM2: NORM2. (line 6)
* NOSHARED: Extended I/O specifiers.
(line 6)
* NOT: NOT. (line 6)
* NULL: NULL. (line 6)
* NUM_IMAGES: NUM_IMAGES. (line 6)
* open, action: Files opened without an explicit ACTION= specifier.
(line 6)
* OpenACC <1>: OpenACC. (line 6)
* OpenACC: Fortran Dialect Options.
(line 138)
* OpenMP <1>: OpenMP. (line 6)
* OpenMP: Fortran Dialect Options.
(line 150)
* operators, unary: Unary operators. (line 6)
* operators, xor: .XOR. operator. (line 6)
* options inquiry function: COMPILER_OPTIONS. (line 6)
* options, code generation: Code Gen Options. (line 6)
* options, debugging: Debugging Options. (line 6)
* options, dialect: Fortran Dialect Options.
(line 6)
* options, directory search: Directory Options. (line 6)
* options, errors: Error and Warning Options.
(line 6)
* options, Fortran dialect: Fortran Dialect Options.
(line 11)
* options, gfortran command: Invoking GNU Fortran.
(line 6)
* options, linking: Link Options. (line 6)
* options, negative forms: Invoking GNU Fortran.
(line 13)
* options, preprocessor: Preprocessing Options.
(line 6)
* options, real kind type promotion: Fortran Dialect Options.
(line 230)
* options, run-time: Code Gen Options. (line 6)
* options, runtime: Runtime Options. (line 6)
* options, warnings: Error and Warning Options.
(line 6)
* OR: OR. (line 6)
* output, newline: NEW_LINE. (line 6)
* PACK: PACK. (line 6)
* PARAMETER: Legacy PARAMETER statements.
(line 6)
* parity: POPPAR. (line 6)
* Parity: PARITY. (line 6)
* PARITY: PARITY. (line 6)
* paths, search: Directory Options. (line 14)
* PERROR: PERROR. (line 6)
* pointer checking: Code Gen Options. (line 146)
* pointer, C address of pointers: C_F_PROCPOINTER. (line 6)
* pointer, C address of procedures: C_FUNLOC. (line 6)
* pointer, C association status: C_ASSOCIATED. (line 6)
* pointer, convert C to Fortran: C_F_POINTER. (line 6)
* pointer, cray <1>: MALLOC. (line 6)
* pointer, cray: FREE. (line 6)
* pointer, Cray: Cray pointers. (line 6)
* pointer, disassociated: NULL. (line 6)
* pointer, status <1>: NULL. (line 6)
* pointer, status: ASSOCIATED. (line 6)
* POPCNT: POPCNT. (line 6)
* POPPAR: POPPAR. (line 6)
* positive difference: DIM. (line 6)
* PRECISION: PRECISION. (line 6)
* Preprocessing: Preprocessing and conditional compilation.
(line 6)
* preprocessing, assertion: Preprocessing Options.
(line 114)
* preprocessing, define macros: Preprocessing Options.
(line 153)
* preprocessing, include path: Preprocessing Options.
(line 70)
* preprocessing, keep comments: Preprocessing Options.
(line 123)
* preprocessing, no linemarkers: Preprocessing Options.
(line 181)
* preprocessing, undefine macros: Preprocessing Options.
(line 187)
* preprocessor: Preprocessing Options.
(line 6)
* preprocessor, debugging: Preprocessing Options.
(line 26)
* preprocessor, disable: Preprocessing Options.
(line 12)
* preprocessor, enable: Preprocessing Options.
(line 12)
* preprocessor, include file handling: Preprocessing and conditional compilation.
(line 6)
* preprocessor, working directory: Preprocessing Options.
(line 55)
* PRESENT: PRESENT. (line 6)
* private: Fortran Dialect Options.
(line 91)
* procedure pointer, convert C to Fortran: C_LOC. (line 6)
* process ID: GETPID. (line 6)
* PRODUCT: PRODUCT. (line 6)
* product, double-precision: DPROD. (line 6)
* product, matrix: MATMUL. (line 6)
* product, vector: DOT_PRODUCT. (line 6)
* program termination: EXIT. (line 6)
* program termination, with core dump: ABORT. (line 6)
* PROTECTED statement: Fortran 2003 status. (line 115)
* Q edit descriptor: Q edit descriptor. (line 6)
* Q exponent-letter: Q exponent-letter. (line 6)
* RADIX: RADIX. (line 6)
* radix, real: SELECTED_REAL_KIND. (line 6)
* RAN: RAN. (line 6)
* RAND: RAND. (line 6)
* random number generation <1>: RANDOM_NUMBER. (line 6)
* random number generation <2>: RAND. (line 6)
* random number generation <3>: RAN. (line 6)
* random number generation: IRAND. (line 6)
* random number generation, initialization: RANDOM_INIT. (line 6)
* random number generation, seeding <1>: SRAND. (line 6)
* random number generation, seeding: RANDOM_SEED. (line 6)
* RANDOM_INIT: RANDOM_INIT. (line 6)
* RANDOM_NUMBER: RANDOM_NUMBER. (line 6)
* RANDOM_SEED: RANDOM_SEED. (line 6)
* RANGE: RANGE. (line 6)
* range checking: Code Gen Options. (line 146)
* rank: RANK. (line 6)
* RANK: RANK. (line 6)
* re-association of parenthesized expressions: Code Gen Options.
(line 396)
* read character, stream mode <1>: FGETC. (line 6)
* read character, stream mode: FGET. (line 6)
* READONLY: Extended I/O specifiers.
(line 6)
* REAL: REAL. (line 6)
* real kind: SELECTED_REAL_KIND. (line 6)
* real number, exponent: EXPONENT. (line 6)
* real number, fraction: FRACTION. (line 6)
* real number, nearest different: NEAREST. (line 6)
* real number, relative spacing <1>: SPACING. (line 6)
* real number, relative spacing: RRSPACING. (line 6)
* real number, scale: SCALE. (line 6)
* real number, set exponent: SET_EXPONENT. (line 6)
* Reallocate the LHS in assignments: Code Gen Options. (line 405)
* Reallocate the LHS in assignments, notification: Error and Warning Options.
(line 237)
* REALPART: REAL. (line 6)
* RECORD: STRUCTURE and RECORD.
(line 6)
* record marker: File format of unformatted sequential files.
(line 6)
* Reduction, XOR: PARITY. (line 6)
* remainder: MOD. (line 6)
* RENAME: RENAME. (line 6)
* repacking arrays: Code Gen Options. (line 286)
* REPEAT: REPEAT. (line 6)
* RESHAPE: RESHAPE. (line 6)
* REWIND: Read/Write after EOF marker.
(line 6)
* right shift, combined: DSHIFTR. (line 6)
* root: SQRT. (line 6)
* rounding, ceiling <1>: CEILING. (line 6)
* rounding, ceiling: ANINT. (line 6)
* rounding, floor <1>: FLOOR. (line 6)
* rounding, floor: AINT. (line 6)
* rounding, nearest whole number: NINT. (line 6)
* RRSPACING: RRSPACING. (line 6)
* RSHIFT: RSHIFT. (line 6)
* run-time checking: Code Gen Options. (line 146)
* SAME_TYPE_AS: SAME_TYPE_AS. (line 6)
* SAVE statement: Code Gen Options. (line 15)
* SCALE: SCALE. (line 6)
* SCAN: SCAN. (line 6)
* search path: Directory Options. (line 6)
* search paths, for included files: Directory Options. (line 14)
* SECNDS: SECNDS. (line 6)
* SECOND: SECOND. (line 6)
* seeding a random number generator <1>: SRAND. (line 6)
* seeding a random number generator: RANDOM_SEED. (line 6)
* SELECTED_CHAR_KIND: SELECTED_CHAR_KIND. (line 6)
* SELECTED_INT_KIND: SELECTED_INT_KIND. (line 6)
* SELECTED_REAL_KIND: SELECTED_REAL_KIND. (line 6)
* sequential, unformatted: File format of unformatted sequential files.
(line 6)
* SET_EXPONENT: SET_EXPONENT. (line 6)
* SHAPE: SHAPE. (line 6)
* SHARE: Extended I/O specifiers.
(line 6)
* SHARED: Extended I/O specifiers.
(line 6)
* shift, left <1>: SHIFTL. (line 6)
* shift, left: DSHIFTL. (line 6)
* shift, right <1>: SHIFTR. (line 6)
* shift, right: DSHIFTR. (line 6)
* shift, right with fill: SHIFTA. (line 6)
* SHIFTA: SHIFTA. (line 6)
* SHIFTL: SHIFTL. (line 6)
* SHIFTR: SHIFTR. (line 6)
* SHORT: INT2. (line 6)
* SIGN: SIGN. (line 6)
* sign copying: SIGN. (line 6)
* SIGNAL: SIGNAL. (line 6)
* SIN: SIN. (line 6)
* SIND: SIND. (line 6)
* sine: SIN. (line 6)
* sine, degrees: SIND. (line 6)
* sine, hyperbolic: SINH. (line 6)
* sine, hyperbolic, inverse: ASINH. (line 6)
* sine, inverse: ASIN. (line 6)
* sine, inverse, degrees: ASIND. (line 6)
* SINH: SINH. (line 6)
* SIZE: SIZE. (line 6)
* size of a variable, in bits: BIT_SIZE. (line 6)
* size of an expression <1>: SIZEOF. (line 6)
* size of an expression: C_SIZEOF. (line 6)
* SIZEOF: SIZEOF. (line 6)
* SLEEP: SLEEP. (line 6)
* SNGL: REAL. (line 6)
* SPACING: SPACING. (line 6)
* SPREAD: SPREAD. (line 6)
* SQRT: SQRT. (line 6)
* square-root: SQRT. (line 6)
* SRAND: SRAND. (line 6)
* Standards: Standards. (line 6)
* STAT: STAT. (line 6)
* statement, ENUM: Fortran 2003 status. (line 92)
* statement, ENUMERATOR: Fortran 2003 status. (line 92)
* statement, FLUSH: Fortran 2003 status. (line 88)
* statement, IMPORT: Fortran 2003 status. (line 121)
* statement, ISO_FORTRAN_ENV: Fortran 2003 status. (line 129)
* statement, PROTECTED: Fortran 2003 status. (line 115)
* statement, SAVE: Code Gen Options. (line 15)
* statement, USE, INTRINSIC: Fortran 2003 status. (line 129)
* statement, VALUE: Fortran 2003 status. (line 117)
* statement, VOLATILE: Fortran 2003 status. (line 119)
* STATIC: AUTOMATIC and STATIC attributes.
(line 6)
* storage size: STORAGE_SIZE. (line 6)
* STORAGE_SIZE: STORAGE_SIZE. (line 6)
* STREAM I/O: Fortran 2003 status. (line 104)
* stream mode, read character <1>: FGETC. (line 6)
* stream mode, read character: FGET. (line 6)
* stream mode, write character <1>: FPUTC. (line 6)
* stream mode, write character: FPUT. (line 6)
* string, adjust left: ADJUSTL. (line 6)
* string, adjust right: ADJUSTR. (line 6)
* string, comparison <1>: LLT. (line 6)
* string, comparison <2>: LLE. (line 6)
* string, comparison <3>: LGT. (line 6)
* string, comparison: LGE. (line 6)
* string, concatenate: REPEAT. (line 6)
* string, find missing set: VERIFY. (line 6)
* string, find non-blank character: LNBLNK. (line 6)
* string, find subset: SCAN. (line 6)
* string, find substring: INDEX intrinsic. (line 6)
* string, length: LEN. (line 6)
* string, length, without trailing whitespace: LEN_TRIM. (line 6)
* string, remove trailing whitespace: TRIM. (line 6)
* string, repeat: REPEAT. (line 6)
* strings, varying length: Varying Length Character Strings.
(line 6)
* STRUCTURE: STRUCTURE and RECORD.
(line 6)
* structure packing: Code Gen Options. (line 280)
* subrecord: File format of unformatted sequential files.
(line 6)
* subscript checking: Code Gen Options. (line 146)
* substring position: INDEX intrinsic. (line 6)
* SUM: SUM. (line 6)
* sum array elements: SUM. (line 6)
* suppressing warnings: Error and Warning Options.
(line 6)
* symbol names: Fortran Dialect Options.
(line 73)
* symbol names, transforming: Code Gen Options. (line 57)
* symbol names, underscores: Code Gen Options. (line 57)
* SYMLNK: SYMLNK. (line 6)
* syntax checking: Error and Warning Options.
(line 33)
* SYSTEM: SYSTEM. (line 6)
* system, error handling <1>: PERROR. (line 6)
* system, error handling <2>: IERRNO. (line 6)
* system, error handling: GERROR. (line 6)
* system, group ID: GETGID. (line 6)
* system, host name: HOSTNM. (line 6)
* system, login name: GETLOG. (line 6)
* system, process ID: GETPID. (line 6)
* system, signal handling: SIGNAL. (line 6)
* system, system call <1>: SYSTEM. (line 6)
* system, system call: EXECUTE_COMMAND_LINE.
(line 6)
* system, terminal <1>: TTYNAM. (line 6)
* system, terminal: ISATTY. (line 6)
* system, user ID: GETUID. (line 6)
* system, working directory <1>: GETCWD. (line 6)
* system, working directory: CHDIR. (line 6)
* SYSTEM_CLOCK: SYSTEM_CLOCK. (line 6)
* tabulators: Error and Warning Options.
(line 186)
* TAN: TAN. (line 6)
* TAND: TAND. (line 6)
* tangent: TAN. (line 6)
* tangent, degrees: TAND. (line 6)
* tangent, hyperbolic: TANH. (line 6)
* tangent, hyperbolic, inverse: ATANH. (line 6)
* tangent, inverse <1>: ATAN2. (line 6)
* tangent, inverse: ATAN. (line 6)
* tangent, inverse, degrees <1>: ATAN2D. (line 6)
* tangent, inverse, degrees: ATAND. (line 6)
* TANH: TANH. (line 6)
* terminate program: EXIT. (line 6)
* terminate program, with core dump: ABORT. (line 6)
* THIS_IMAGE: THIS_IMAGE. (line 6)
* thread-safety, threads: Thread-safety of the runtime library.
(line 6)
* TIME: TIME. (line 6)
* time, clock ticks <1>: SYSTEM_CLOCK. (line 6)
* time, clock ticks <2>: MCLOCK8. (line 6)
* time, clock ticks: MCLOCK. (line 6)
* time, conversion to GMT info: GMTIME. (line 6)
* time, conversion to local time info: LTIME. (line 6)
* time, conversion to string: CTIME. (line 6)
* time, current <1>: TIME8. (line 6)
* time, current <2>: TIME. (line 6)
* time, current <3>: ITIME. (line 6)
* time, current <4>: FDATE. (line 6)
* time, current: DATE_AND_TIME. (line 6)
* time, elapsed <1>: SECOND. (line 6)
* time, elapsed <2>: SECNDS. (line 6)
* time, elapsed <3>: ETIME. (line 6)
* time, elapsed <4>: DTIME. (line 6)
* time, elapsed: CPU_TIME. (line 6)
* TIME8: TIME8. (line 6)
* TINY: TINY. (line 6)
* TR 15581: Fortran 2003 status. (line 97)
* trace: Debugging Options. (line 87)
* TRAILZ: TRAILZ. (line 6)
* TRANSFER: TRANSFER. (line 6)
* transforming symbol names: Code Gen Options. (line 57)
* transpose: TRANSPOSE. (line 6)
* TRANSPOSE: TRANSPOSE. (line 6)
* trigonometric function, cosine: COS. (line 6)
* trigonometric function, cosine, degrees: COSD. (line 6)
* trigonometric function, cosine, inverse: ACOS. (line 6)
* trigonometric function, cosine, inverse, degrees: ACOSD. (line 6)
* trigonometric function, cotangent: COTAN. (line 6)
* trigonometric function, cotangent, degrees: COTAND. (line 6)
* trigonometric function, sine: SIN. (line 6)
* trigonometric function, sine, degrees: SIND. (line 6)
* trigonometric function, sine, inverse: ASIN. (line 6)
* trigonometric function, sine, inverse, degrees: ASIND. (line 6)
* trigonometric function, tangent: TAN. (line 6)
* trigonometric function, tangent, degrees: TAND. (line 6)
* trigonometric function, tangent, inverse <1>: ATAN2. (line 6)
* trigonometric function, tangent, inverse: ATAN. (line 6)
* trigonometric function, tangent, inverse, degrees <1>: ATAN2D.
(line 6)
* trigonometric function, tangent, inverse, degrees: ATAND. (line 6)
* TRIM: TRIM. (line 6)
* TTYNAM: TTYNAM. (line 6)
* type alias print: TYPE as an alias for PRINT.
(line 6)
* type cast: TRANSFER. (line 6)
* UBOUND: UBOUND. (line 6)
* UCOBOUND: UCOBOUND. (line 6)
* UMASK: UMASK. (line 6)
* underflow: Error and Warning Options.
(line 199)
* underscore: Code Gen Options. (line 57)
* unformatted sequential: File format of unformatted sequential files.
(line 6)
* UNION: UNION and MAP. (line 6)
* UNLINK: UNLINK. (line 6)
* UNPACK: UNPACK. (line 6)
* unused dummy argument: Error and Warning Options.
(line 215)
* unused parameter: Error and Warning Options.
(line 219)
* USE, INTRINSIC statement: Fortran 2003 status. (line 129)
* user id: GETUID. (line 6)
* VALUE statement: Fortran 2003 status. (line 117)
* variable attributes: AUTOMATIC and STATIC attributes.
(line 6)
* Varying length character strings: Varying Length Character Strings.
(line 6)
* Varying length strings: Varying Length Character Strings.
(line 6)
* vector product: DOT_PRODUCT. (line 6)
* VERIFY: VERIFY. (line 6)
* version of the compiler: COMPILER_VERSION. (line 6)
* VOLATILE: Volatile COMMON blocks.
(line 6)
* VOLATILE statement: Fortran 2003 status. (line 119)
* warning, C binding type: Error and Warning Options.
(line 106)
* warnings, aliasing: Error and Warning Options.
(line 71)
* warnings, alignment of COMMON blocks: Error and Warning Options.
(line 226)
* warnings, all: Error and Warning Options.
(line 62)
* warnings, ampersand: Error and Warning Options.
(line 88)
* warnings, argument mismatch: Error and Warning Options.
(line 96)
* warnings, array temporaries: Error and Warning Options.
(line 101)
* warnings, character truncation: Error and Warning Options.
(line 113)
* warnings, conversion: Error and Warning Options.
(line 122)
* warnings, division of integers: Error and Warning Options.
(line 149)
* warnings, extra: Error and Warning Options.
(line 130)
* warnings, function elimination: Error and Warning Options.
(line 232)
* warnings, implicit interface: Error and Warning Options.
(line 139)
* warnings, implicit procedure: Error and Warning Options.
(line 145)
* warnings, integer division: Error and Warning Options.
(line 149)
* warnings, interface mismatch: Error and Warning Options.
(line 96)
* warnings, intrinsic: Error and Warning Options.
(line 204)
* warnings, intrinsics of other standards: Error and Warning Options.
(line 153)
* warnings, line truncation: Error and Warning Options.
(line 116)
* warnings, loop interchange: Error and Warning Options.
(line 135)
* warnings, non-standard intrinsics: Error and Warning Options.
(line 153)
* warnings, parameter mismatch: Error and Warning Options.
(line 96)
* warnings, q exponent-letter: Error and Warning Options.
(line 160)
* warnings, suppressing: Error and Warning Options.
(line 6)
* warnings, suspicious code: Error and Warning Options.
(line 164)
* warnings, tabs: Error and Warning Options.
(line 186)
* warnings, to errors: Error and Warning Options.
(line 279)
* warnings, undefined do loop: Error and Warning Options.
(line 194)
* warnings, underflow: Error and Warning Options.
(line 199)
* warnings, unused dummy argument: Error and Warning Options.
(line 215)
* warnings, unused parameter: Error and Warning Options.
(line 219)
* warnings, use statements: Error and Warning Options.
(line 211)
* write character, stream mode <1>: FPUTC. (line 6)
* write character, stream mode: FPUT. (line 6)
* XOR: XOR. (line 6)
* XOR reduction: PARITY. (line 6)
* ZABS: ABS. (line 6)
* ZCOS: COS. (line 6)
* ZCOSD: COSD. (line 6)
* zero bits <1>: TRAILZ. (line 6)
* zero bits: LEADZ. (line 6)
* ZEXP: EXP. (line 6)
* ZLOG: LOG. (line 6)
* ZSIN: SIN. (line 6)
* ZSIND: SIND. (line 6)
* ZSQRT: SQRT. (line 6)

Tag Table:
Node: Top2063
Node: Introduction3480
Node: About GNU Fortran4229
Node: GNU Fortran and GCC8230
Node: Preprocessing and conditional compilation10344
Node: GNU Fortran and G7712432
Node: Project Status13005
Node: Standards15749
Node: Varying Length Character Strings17090
Node: Invoking GNU Fortran17841
Node: Option Summary19675
Node: Fortran Dialect Options23691
Node: Preprocessing Options36275
Node: Error and Warning Options44506
Node: Debugging Options56279
Node: Directory Options61048
Node: Link Options62483
Node: Runtime Options63107
Node: Code Gen Options65012
Node: Interoperability Options84869
Node: Environment Variables86949
Node: Runtime87562
Node: TMPDIR88738
Node: GFORTRAN_STDIN_UNIT89407
Node: GFORTRAN_STDOUT_UNIT89789
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Node: Fortran 2008 status103090
Node: Fortran 2018 status108464
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Node: KIND Type Parameters111606
Node: Internal representation of LOGICAL variables113035
Node: Evaluation of logical expressions113892
Node: MAX and MIN intrinsics with REAL NaN arguments114742
Node: Thread-safety of the runtime library115562
Node: Data consistency and durability117968
Node: Files opened without an explicit ACTION= specifier121069
Node: File operations on symbolic links121763
Node: File format of unformatted sequential files122884
Node: Asynchronous I/O125256
Node: Extensions125953
Node: Extensions implemented in GNU Fortran126558
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Node: Old-style variable initialization129564
Node: Extensions to namelist130876
Node: X format descriptor without count field133178
Node: Commas in FORMAT specifications133705
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Node: `Q' exponent-letter135171
Node: BOZ literal constants135771
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Node: Implicitly convert LOGICAL and INTEGER values139063
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Node: Cray pointers141795
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Node: Further Interoperability of Fortran with C196620
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Node: Introduction to Intrinsics315920
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End Tag Table