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<title>The GNU Fortran Compiler: GAMMA</title>
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<a name="GAMMA"></a>
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<p>
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Next: <a href="GERROR.html#GERROR" accesskey="n" rel="next">GERROR</a>, Previous: <a href="FTELL.html#FTELL" accesskey="p" rel="prev">FTELL</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="GAMMA-_002d_002d_002d-Gamma-function"></a>
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<h3 class="section">9.111 <code>GAMMA</code> — Gamma function</h3>
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<a name="index-GAMMA"></a>
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<a name="index-DGAMMA"></a>
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<a name="index-Gamma-function"></a>
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<a name="index-Factorial-function"></a>
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<dl compact="compact">
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<dt><em>Description</em>:</dt>
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<dd><p><code>GAMMA(X)</code> computes Gamma (<em>\Gamma</em>) of <var>X</var>. For positive,
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integer values of <var>X</var> the Gamma function simplifies to the factorial
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function <em>\Gamma(x)=(x-1)!</em>.
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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 2008 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>Elemental function
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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>X = GAMMA(X)</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>X</var></td><td width="70%">Shall be of type <code>REAL</code> and neither zero
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nor a negative integer.</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>The return value is of type <code>REAL</code> of the same kind as <var>X</var>.
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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_gamma
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real :: x = 1.0
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x = gamma(x) ! returns 1.0
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end program test_gamma
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</pre></div>
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</dd>
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<dt><em>Specific names</em>:</dt>
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<dd><table>
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<tr><td width="20%">Name</td><td width="20%">Argument</td><td width="20%">Return type</td><td width="25%">Standard</td></tr>
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<tr><td width="20%"><code>GAMMA(X)</code></td><td width="20%"><code>REAL(4) X</code></td><td width="20%"><code>REAL(4)</code></td><td width="25%">GNU Extension</td></tr>
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<tr><td width="20%"><code>DGAMMA(X)</code></td><td width="20%"><code>REAL(8) X</code></td><td width="20%"><code>REAL(8)</code></td><td width="25%">GNU Extension</td></tr>
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</table>
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</dd>
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<dt><em>See also</em>:</dt>
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<dd><p>Logarithm of the Gamma function: <a href="LOG_005fGAMMA.html#LOG_005fGAMMA">LOG_GAMMA</a>
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</p>
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