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| author | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
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| committer | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
| commit | abdaadbcae30fe0c9a66c7516798279fdfd97750 (patch) | |
| tree | 00a54a6e25601e43876d03c1a4a12a749d4a914c /share/doc/gfortran/RANDOM_005fSEED.html | |
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diff --git a/share/doc/gfortran/RANDOM_005fSEED.html b/share/doc/gfortran/RANDOM_005fSEED.html new file mode 100644 index 0000000..3765cdb --- /dev/null +++ b/share/doc/gfortran/RANDOM_005fSEED.html @@ -0,0 +1,164 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- Copyright (C) 1999-2023 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. --> +<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ --> +<head> +<title>The GNU Fortran Compiler: RANDOM_SEED</title> + +<meta name="description" content="The GNU Fortran Compiler: RANDOM_SEED"> +<meta name="keywords" content="The GNU Fortran Compiler: RANDOM_SEED"> +<meta name="resource-type" content="document"> +<meta name="distribution" content="global"> +<meta name="Generator" content="makeinfo"> +<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> +<link href="index.html#Top" rel="start" title="Top"> +<link href="Option-Index.html#Option-Index" rel="index" title="Option Index"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="Intrinsic-Procedures.html#Intrinsic-Procedures" rel="up" title="Intrinsic Procedures"> +<link href="RANGE.html#RANGE" rel="next" title="RANGE"> +<link href="RANDOM_005fNUMBER.html#RANDOM_005fNUMBER" rel="previous" title="RANDOM_NUMBER"> +<style type="text/css"> +<!-- +a.summary-letter {text-decoration: none} +blockquote.smallquotation {font-size: smaller} +div.display {margin-left: 3.2em} +div.example {margin-left: 3.2em} +div.indentedblock {margin-left: 3.2em} +div.lisp {margin-left: 3.2em} +div.smalldisplay {margin-left: 3.2em} +div.smallexample {margin-left: 3.2em} +div.smallindentedblock {margin-left: 3.2em; font-size: smaller} +div.smalllisp {margin-left: 3.2em} +kbd {font-style:oblique} +pre.display {font-family: inherit} +pre.format {font-family: inherit} +pre.menu-comment {font-family: serif} +pre.menu-preformatted {font-family: serif} +pre.smalldisplay {font-family: inherit; font-size: smaller} +pre.smallexample {font-size: smaller} +pre.smallformat {font-family: inherit; font-size: smaller} +pre.smalllisp {font-size: smaller} +span.nocodebreak {white-space:nowrap} +span.nolinebreak {white-space:nowrap} +span.roman {font-family:serif; font-weight:normal} +span.sansserif {font-family:sans-serif; font-weight:normal} +ul.no-bullet {list-style: none} +--> +</style> + + +</head> + +<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> +<a name="RANDOM_005fSEED"></a> +<div class="header"> +<p> +Next: <a href="RANGE.html#RANGE" accesskey="n" rel="next">RANGE</a>, Previous: <a href="RANDOM_005fNUMBER.html#RANDOM_005fNUMBER" accesskey="p" rel="previous">RANDOM_NUMBER</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> +</div> +<hr> +<a name="RANDOM_005fSEED-_002d_002d_002d-Initialize-a-pseudo_002drandom-number-sequence"></a> +<h3 class="section">8.225 <code>RANDOM_SEED</code> — Initialize a pseudo-random number sequence</h3> +<a name="index-RANDOM_005fSEED"></a> +<a name="index-random-number-generation_002c-seeding"></a> +<a name="index-seeding-a-random-number-generator"></a> + +<dl compact="compact"> +<dt><em>Description</em>:</dt> +<dd><p>Restarts or queries the state of the pseudorandom number generator used by +<code>RANDOM_NUMBER</code>. +</p> +<p>If <code>RANDOM_SEED</code> is called without arguments, it is seeded with +random data retrieved from the operating system. +</p> +<p>As an extension to the Fortran standard, the GFortran +<code>RANDOM_NUMBER</code> supports multiple threads. Each thread in a +multi-threaded program has its own seed. When <code>RANDOM_SEED</code> is +called either without arguments or with the <var>PUT</var> argument, the +given seed is copied into a master seed as well as the seed of the +current thread. When a new thread uses <code>RANDOM_NUMBER</code> for the +first time, the seed is copied from the master seed, and forwarded +<em>N * 2^{128}</em> steps to guarantee that the random stream does not +alias any other stream in the system, where <var>N</var> is the number of +threads that have used <code>RANDOM_NUMBER</code> so far during the program +execution. +</p> +</dd> +<dt><em>Standard</em>:</dt> +<dd><p>Fortran 90 and later +</p> +</dd> +<dt><em>Class</em>:</dt> +<dd><p>Subroutine +</p> +</dd> +<dt><em>Syntax</em>:</dt> +<dd><p><code>CALL RANDOM_SEED([SIZE, PUT, GET])</code> +</p> +</dd> +<dt><em>Arguments</em>:</dt> +<dd><table> +<tr><td width="15%"><var>SIZE</var></td><td width="70%">(Optional) Shall be a scalar and of type default +<code>INTEGER</code>, with <code>INTENT(OUT)</code>. It specifies the minimum size +of the arrays used with the <var>PUT</var> and <var>GET</var> arguments.</td></tr> +<tr><td width="15%"><var>PUT</var></td><td width="70%">(Optional) Shall be an array of type default +<code>INTEGER</code> and rank one. It is <code>INTENT(IN)</code> and the size of +the array must be larger than or equal to the number returned by the +<var>SIZE</var> argument.</td></tr> +<tr><td width="15%"><var>GET</var></td><td width="70%">(Optional) Shall be an array of type default +<code>INTEGER</code> and rank one. It is <code>INTENT(OUT)</code> and the size +of the array must be larger than or equal to the number returned by +the <var>SIZE</var> argument.</td></tr> +</table> + +</dd> +<dt><em>Example</em>:</dt> +<dd><div class="smallexample"> +<pre class="smallexample">program test_random_seed + implicit none + integer, allocatable :: seed(:) + integer :: n + + call random_seed(size = n) + allocate(seed(n)) + call random_seed(get=seed) + write (*, *) seed +end program test_random_seed +</pre></div> + +</dd> +<dt><em>See also</em>:</dt> +<dd><p><a href="RANDOM_005fNUMBER.html#RANDOM_005fNUMBER">RANDOM_NUMBER</a>, <br> +<a href="RANDOM_005fINIT.html#RANDOM_005fINIT">RANDOM_INIT</a> +</p></dd> +</dl> + + + +<hr> +<div class="header"> +<p> +Next: <a href="RANGE.html#RANGE" accesskey="n" rel="next">RANGE</a>, Previous: <a href="RANDOM_005fNUMBER.html#RANDOM_005fNUMBER" accesskey="p" rel="previous">RANDOM_NUMBER</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> +</div> + + + +</body> +</html> |