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| Previous: <a href="Bignums.html#Bignums" accesskey="p" rel="prev">Bignums</a>, Up: <a href="Numbers.html#Numbers" accesskey="u" rel="up">Numbers</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p> |
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| <a name="Flonums-1"></a> |
| <h4 class="subsubsection">3.6.2.3 Flonums</h4> |
| <a name="index-flonums"></a> |
| <a name="index-floating-point-numbers"></a> |
| <a name="index-constants_002c-floating-point"></a> |
| |
| <a name="index-precision_002c-floating-point"></a> |
| <p>A <em>flonum</em> represents a floating point number. The translation is |
| indirect: a decimal floating point number from the text is converted by |
| <code>as</code> to a generic binary floating point number of more than |
| sufficient precision. This generic floating point number is converted |
| to a particular computer’s floating point format (or formats) by a |
| portion of <code>as</code> specialized to that computer. |
| </p> |
| <p>A flonum is written by writing (in order) |
| </p><ul> |
| <li> The digit ‘<samp>0</samp>’. |
| (‘<samp>0</samp>’ is optional on the HPPA.) |
| |
| </li><li> A letter, to tell <code>as</code> the rest of the number is a flonum. |
| <kbd>e</kbd> is recommended. Case is not important. |
| |
| <p>On the H8/300, Renesas / SuperH SH, |
| and AMD 29K architectures, the letter must be |
| one of the letters ‘<samp>DFPRSX</samp>’ (in upper or lower case). |
| </p> |
| <p>On the ARC, the letter must be one of the letters ‘<samp>DFRS</samp>’ |
| (in upper or lower case). |
| </p> |
| <p>On the Intel 960 architecture, the letter must be |
| one of the letters ‘<samp>DFT</samp>’ (in upper or lower case). |
| </p> |
| <p>On the HPPA architecture, the letter must be ‘<samp>E</samp>’ (upper case only). |
| </p> |
| </li><li> An optional sign: either ‘<samp>+</samp>’ or ‘<samp>-</samp>’. |
| |
| </li><li> An optional <em>integer part</em>: zero or more decimal digits. |
| |
| </li><li> An optional <em>fractional part</em>: ‘<samp>.</samp>’ followed by zero |
| or more decimal digits. |
| |
| </li><li> An optional exponent, consisting of: |
| |
| <ul> |
| <li> An ‘<samp>E</samp>’ or ‘<samp>e</samp>’. |
| </li><li> Optional sign: either ‘<samp>+</samp>’ or ‘<samp>-</samp>’. |
| </li><li> One or more decimal digits. |
| </li></ul> |
| |
| </li></ul> |
| |
| <p>At least one of the integer part or the fractional part must be |
| present. The floating point number has the usual base-10 value. |
| </p> |
| <p><code>as</code> does all processing using integers. Flonums are computed |
| independently of any floating point hardware in the computer running |
| <code>as</code>. |
| </p> |
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| Previous: <a href="Bignums.html#Bignums" accesskey="p" rel="prev">Bignums</a>, Up: <a href="Numbers.html#Numbers" accesskey="u" rel="up">Numbers</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p> |
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