140 lines
5.2 KiB
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140 lines
5.2 KiB
HTML
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<head>
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<title>The GNU Fortran Compiler: IRAND</title>
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
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<a name="IRAND"></a>
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<div class="header">
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<p>
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Next: <a href="IS_005fIOSTAT_005fEND.html#IS_005fIOSTAT_005fEND" accesskey="n" rel="next">IS_IOSTAT_END</a>, Previous: <a href="IPARITY.html#IPARITY" accesskey="p" rel="prev">IPARITY</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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</div>
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<hr>
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<a name="IRAND-_002d_002d_002d-Integer-pseudo_002drandom-number"></a>
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<h3 class="section">9.146 <code>IRAND</code> — Integer pseudo-random number</h3>
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<a name="index-IRAND"></a>
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<a name="index-random-number-generation"></a>
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<dl compact="compact">
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<dt><em>Description</em>:</dt>
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<dd><p><code>IRAND(FLAG)</code> returns a pseudo-random number from a uniform
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distribution between 0 and a system-dependent limit (which is in most
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cases 2147483647). If <var>FLAG</var> is 0, the next number
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in the current sequence is returned; if <var>FLAG</var> is 1, the generator
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is restarted by <code>CALL SRAND(0)</code>; if <var>FLAG</var> has any other value,
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it is used as a new seed with <code>SRAND</code>.
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</p>
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<p>This intrinsic routine is provided for backwards compatibility with
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GNU Fortran 77. It implements a simple modulo generator as provided
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by <code>g77</code>. For new code, one should consider the use of
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<a href="RANDOM_005fNUMBER.html#RANDOM_005fNUMBER">RANDOM_NUMBER</a> as it implements a superior algorithm.
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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>GNU extension
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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>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>RESULT = IRAND(I)</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>I</var></td><td width="70%">Shall be a scalar <code>INTEGER</code> of kind 4.</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 <code>INTEGER(kind=4)</code> type.
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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_irand
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integer,parameter :: seed = 86456
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call srand(seed)
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print *, irand(), irand(), irand(), irand()
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print *, irand(seed), irand(), irand(), irand()
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end program test_irand
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</pre></div>
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</dd>
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</dl>
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