<html lang="en"> <head> <title>RAND - The GNU Fortran Compiler</title> <meta http-equiv="Content-Type" content="text/html"> <meta name="description" content="The GNU Fortran Compiler"> <meta name="generator" content="makeinfo 4.13"> <link title="Top" rel="start" href="index.html#Top"> <link rel="up" href="Intrinsic-Procedures.html#Intrinsic-Procedures" title="Intrinsic Procedures"> <link rel="prev" href="RANDOM_005fSEED.html#RANDOM_005fSEED" title="RANDOM_SEED"> <link rel="next" href="RANGE.html#RANGE" title="RANGE"> <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> <!-- Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with the Invariant Sections being ``Funding Free Software'', the Front-Cover Texts being (a) (see below), and with the Back-Cover Texts being (b) (see below). A copy of the license is included in the section entitled ``GNU Free Documentation License''. (a) The FSF's Front-Cover Text is: A GNU Manual (b) The FSF's Back-Cover Text is: You have freedom to copy and modify this GNU Manual, like GNU software. Copies published by the Free Software Foundation raise funds for GNU development.--> <meta http-equiv="Content-Style-Type" content="text/css"> <style type="text/css"><!-- pre.display { font-family:inherit } pre.format { font-family:inherit } pre.smalldisplay { font-family:inherit; font-size:smaller } pre.smallformat { font-family:inherit; font-size:smaller } pre.smallexample { font-size:smaller } pre.smalllisp { font-size:smaller } span.sc { font-variant:small-caps } span.roman { font-family:serif; font-weight:normal; } span.sansserif { font-family:sans-serif; font-weight:normal; } --></style> </head> <body> <div class="node"> <a name="RAND"></a> <p> Next: <a rel="next" accesskey="n" href="RANGE.html#RANGE">RANGE</a>, Previous: <a rel="previous" accesskey="p" href="RANDOM_005fSEED.html#RANDOM_005fSEED">RANDOM_SEED</a>, Up: <a rel="up" accesskey="u" href="Intrinsic-Procedures.html#Intrinsic-Procedures">Intrinsic Procedures</a> <hr> </div> <h3 class="section">8.196 <code>RAND</code> — Real pseudo-random number</h3> <p><a name="index-RAND-931"></a><a name="index-random-number-generation-932"></a> <dl> <dt><em>Description</em>:<dd><code>RAND(FLAG)</code> returns a pseudo-random number from a uniform distribution between 0 and 1. If <var>FLAG</var> is 0, the next number in the current sequence is returned; if <var>FLAG</var> is 1, the generator is restarted by <code>CALL SRAND(0)</code>; if <var>FLAG</var> has any other value, it is used as a new seed with <code>SRAND</code>. <p>This intrinsic routine is provided for backwards compatibility with GNU Fortran 77. It implements a simple modulo generator as provided by <samp><span class="command">g77</span></samp>. For new code, one should consider the use of <a href="RANDOM_005fNUMBER.html#RANDOM_005fNUMBER">RANDOM_NUMBER</a> as it implements a superior algorithm. <br><dt><em>Standard</em>:<dd>GNU extension <br><dt><em>Class</em>:<dd>Function <br><dt><em>Syntax</em>:<dd><code>RESULT = RAND(I)</code> <br><dt><em>Arguments</em>:<dd> <p><table summary=""><tr align="left"><td valign="top" width="15%"><var>I</var> </td><td valign="top" width="70%">Shall be a scalar <code>INTEGER</code> of kind 4. <br></td></tr></table> <br><dt><em>Return value</em>:<dd>The return value is of <code>REAL</code> type and the default kind. <br><dt><em>Example</em>:<dd> <pre class="smallexample"> program test_rand integer,parameter :: seed = 86456 call srand(seed) print *, rand(), rand(), rand(), rand() print *, rand(seed), rand(), rand(), rand() end program test_rand </pre> <br><dt><em>See also</em>:<dd><a href="SRAND.html#SRAND">SRAND</a>, <a href="RANDOM_005fNUMBER.html#RANDOM_005fNUMBER">RANDOM_NUMBER</a> </dl> </body></html>