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111 lines
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Copyright (C) 2024 Tomas Volf
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<title>SRFI-27 Random Sources (Guile Reference Manual)</title>
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<div class="subsubsection-level-extent" id="SRFI_002d27-Random-Sources">
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Next: <a href="SRFI_002d27-Random-Number-Generators.html" accesskey="n" rel="next">Obtaining random number generator procedures</a>, Previous: <a href="SRFI_002d27-Default-Random-Source.html" accesskey="p" rel="prev">The Default Random Source</a>, Up: <a href="SRFI_002d27.html" accesskey="u" rel="up">SRFI-27 - Sources of Random Bits</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
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<h4 class="subsubsection" id="Random-Sources"><span>7.5.19.2 Random Sources<a class="copiable-link" href="#Random-Sources"> ¶</a></span></h4>
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<a class="index-entry-id" id="index-SRFI_002d27-2"></a>
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<dl class="first-deffn first-defun-alias-first-deffn">
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<dt class="deffn defun-alias-deffn" id="index-make_002drandom_002dsource"><span class="category-def">Function: </span><span><strong class="def-name">make-random-source</strong><a class="copiable-link" href="#index-make_002drandom_002dsource"> ¶</a></span></dt>
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<dd><p>Create a new random source. The stream of random numbers obtained from
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each random source created by this procedure will be identical, unless
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its state is changed by one of the procedures below.
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</p></dd></dl>
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<dl class="first-deffn first-defun-alias-first-deffn">
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<dt class="deffn defun-alias-deffn" id="index-random_002dsource_003f"><span class="category-def">Function: </span><span><strong class="def-name">random-source?</strong> <var class="def-var-arguments">object</var><a class="copiable-link" href="#index-random_002dsource_003f"> ¶</a></span></dt>
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<dd><p>Tests whether <var class="var">object</var> is a random source. Random sources are a
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disjoint type.
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</p></dd></dl>
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<dl class="first-deffn first-defun-alias-first-deffn">
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<dt class="deffn defun-alias-deffn" id="index-random_002dsource_002drandomize_0021"><span class="category-def">Function: </span><span><strong class="def-name">random-source-randomize!</strong> <var class="def-var-arguments">source</var><a class="copiable-link" href="#index-random_002dsource_002drandomize_0021"> ¶</a></span></dt>
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<dd><p>Attempt to set the state of the random source to a truly random value.
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The current implementation uses a seed based on the current system time.
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</p></dd></dl>
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<dl class="first-deffn first-defun-alias-first-deffn">
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<dt class="deffn defun-alias-deffn" id="index-random_002dsource_002dpseudo_002drandomize_0021"><span class="category-def">Function: </span><span><strong class="def-name">random-source-pseudo-randomize!</strong> <var class="def-var-arguments">source i j</var><a class="copiable-link" href="#index-random_002dsource_002dpseudo_002drandomize_0021"> ¶</a></span></dt>
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<dd><p>Changes the state of the random source s into the initial state of the
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(<var class="var">i</var>, <var class="var">j</var>)-th independent random source, where <var class="var">i</var> and
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<var class="var">j</var> are non-negative integers. This procedure provides a mechanism
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to obtain a large number of independent random sources (usually all
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derived from the same backbone generator), indexed by two integers. In
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contrast to <code class="code">random-source-randomize!</code>, this procedure is entirely
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deterministic.
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</p></dd></dl>
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<p>The state associated with a random state can be obtained an reinstated
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with the following procedures:
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</p>
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<dl class="first-deffn first-defun-alias-first-deffn">
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<dt class="deffn defun-alias-deffn" id="index-random_002dsource_002dstate_002dref"><span class="category-def">Function: </span><span><strong class="def-name">random-source-state-ref</strong> <var class="def-var-arguments">source</var><a class="copiable-link" href="#index-random_002dsource_002dstate_002dref"> ¶</a></span></dt>
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<dt class="deffnx defunx-alias-deffnx def-cmd-deffn" id="index-random_002dsource_002dstate_002dset_0021"><span class="category-def">Function: </span><span><strong class="def-name">random-source-state-set!</strong> <var class="def-var-arguments">source state</var><a class="copiable-link" href="#index-random_002dsource_002dstate_002dset_0021"> ¶</a></span></dt>
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<dd><p>Get and set the state of a random source. No assumptions should be made
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about the nature of the state object, besides it having an external
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representation (i.e. it can be passed to <code class="code">write</code> and subsequently
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<code class="code">read</code> back).
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</p></dd></dl>
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Next: <a href="SRFI_002d27-Random-Number-Generators.html">Obtaining random number generator procedures</a>, Previous: <a href="SRFI_002d27-Default-Random-Source.html">The Default Random Source</a>, Up: <a href="SRFI_002d27.html">SRFI-27 - Sources of Random Bits</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
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