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| <a name="CPU_005fTIME"></a> |
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| <a name="CPU_005fTIME-_002d_002d_002d-CPU-elapsed-time-in-seconds"></a> |
| <h3 class="section">8.58 <code>CPU_TIME</code> — CPU elapsed time in seconds</h3> |
| <a name="index-CPU_005fTIME"></a> |
| <a name="index-time_002c-elapsed"></a> |
| |
| <dl compact="compact"> |
| <dt><em>Description</em>:</dt> |
| <dd><p>Returns a <code>REAL</code> value representing the elapsed CPU time in |
| seconds. This is useful for testing segments of code to determine |
| execution time. |
| </p> |
| <p>If a time source is available, time will be reported with microsecond |
| resolution. If no time source is available, <var>TIME</var> is set to |
| <code>-1.0</code>. |
| </p> |
| <p>Note that <var>TIME</var> may contain a, system dependent, arbitrary offset |
| and may not start with <code>0.0</code>. For <code>CPU_TIME</code>, the absolute |
| value is meaningless, only differences between subsequent calls to |
| this subroutine, as shown in the example below, should be used. |
| </p> |
| |
| </dd> |
| <dt><em>Standard</em>:</dt> |
| <dd><p>Fortran 95 and later |
| </p> |
| </dd> |
| <dt><em>Class</em>:</dt> |
| <dd><p>Subroutine |
| </p> |
| </dd> |
| <dt><em>Syntax</em>:</dt> |
| <dd><p><code>CALL CPU_TIME(TIME)</code> |
| </p> |
| </dd> |
| <dt><em>Arguments</em>:</dt> |
| <dd><table> |
| <tr><td width="15%"><var>TIME</var></td><td width="70%">The type shall be <code>REAL</code> with <code>INTENT(OUT)</code>.</td></tr> |
| </table> |
| |
| </dd> |
| <dt><em>Return value</em>:</dt> |
| <dd><p>None |
| </p> |
| </dd> |
| <dt><em>Example</em>:</dt> |
| <dd><div class="smallexample"> |
| <pre class="smallexample">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 |
| </pre></div> |
| |
| </dd> |
| <dt><em>See also</em>:</dt> |
| <dd><p><a href="SYSTEM_005fCLOCK.html#SYSTEM_005fCLOCK">SYSTEM_CLOCK</a>, <a href="DATE_005fAND_005fTIME.html#DATE_005fAND_005fTIME">DATE_AND_TIME</a> |
| </p></dd> |
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