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<title>The GNU Fortran Compiler: CPU_TIME</title>
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<a name="CPU_005fTIME"></a>
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<p>
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Next: <a href="CSHIFT.html#CSHIFT" accesskey="n" rel="next">CSHIFT</a>, Previous: <a href="COUNT.html#COUNT" accesskey="p" rel="prev">COUNT</a>, Up: <a href="Intrinsic-Procedures.html#Intrinsic-Procedures" accesskey="u" rel="up">Intrinsic Procedures</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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<hr>
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<a name="CPU_005fTIME-_002d_002d_002d-CPU-elapsed-time-in-seconds"></a>
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<h3 class="section">9.72 <code>CPU_TIME</code> — CPU elapsed time in seconds</h3>
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<a name="index-CPU_005fTIME"></a>
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<a name="index-time_002c-elapsed"></a>
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<dl compact="compact">
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<dt><em>Description</em>:</dt>
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<dd><p>Returns a <code>REAL</code> value representing the elapsed CPU time in
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seconds. This is useful for testing segments of code to determine
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execution time.
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</p>
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<p>If a time source is available, time will be reported with microsecond
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resolution. If no time source is available, <var>TIME</var> is set to
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<code>-1.0</code>.
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</p>
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<p>Note that <var>TIME</var> may contain a, system dependent, arbitrary offset
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and may not start with <code>0.0</code>. For <code>CPU_TIME</code>, the absolute
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value is meaningless, only differences between subsequent calls to
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this subroutine, as shown in the example below, should be used.
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</p>
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</dd>
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<dt><em>Standard</em>:</dt>
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<dd><p>Fortran 95 and later
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</p>
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</dd>
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<dt><em>Class</em>:</dt>
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<dd><p>Subroutine
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</p>
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</dd>
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<dt><em>Syntax</em>:</dt>
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<dd><p><code>CALL CPU_TIME(TIME)</code>
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</p>
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</dd>
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<dt><em>Arguments</em>:</dt>
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<dd><table>
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<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>
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</table>
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</dd>
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<dt><em>Return value</em>:</dt>
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<dd><p>None
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</p>
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</dd>
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<dt><em>Example</em>:</dt>
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<dd><div class="smallexample">
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<pre class="smallexample">program test_cpu_time
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real :: start, finish
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call cpu_time(start)
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! put code to test here
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call cpu_time(finish)
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print '("Time = ",f6.3," seconds.")',finish-start
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end program test_cpu_time
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</pre></div>
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</dd>
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<dt><em>See also</em>:</dt>
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<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>
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</p></dd>
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