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| <a name="boost.random.inversive_congruential"></a><div class="titlepage"></div> |
| <div class="refnamediv"> |
| <h2><span class="refentrytitle">Class template inversive_congruential</span></h2> |
| <p>boost::random::inversive_congruential</p> |
| </div> |
| <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> |
| <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: <<a class="link" href="../../boost_random/reference.html#header.boost.random.inversive_congruential_hpp" title="Header <boost/random/inversive_congruential.hpp>">boost/random/inversive_congruential.hpp</a>> |
| |
| </span><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> IntType<span class="special">,</span> <span class="identifier">IntType</span> a<span class="special">,</span> <span class="identifier">IntType</span> b<span class="special">,</span> <span class="identifier">IntType</span> p<span class="special">,</span> <span class="identifier">IntType</span> val<span class="special">></span> |
| <span class="keyword">class</span> <a class="link" href="inversive_congruential.html" title="Class template inversive_congruential">inversive_congruential</a> <span class="special">{</span> |
| <span class="keyword">public</span><span class="special">:</span> |
| <span class="comment">// types</span> |
| <span class="keyword">typedef</span> <span class="identifier">IntType</span> <a name="boost.random.inversive_congruential.result_type"></a><span class="identifier">result_type</span><span class="special">;</span> |
| |
| <span class="comment">// <a class="link" href="inversive_congruential.html#boost.random.inversive_congruentialconstruct-copy-destruct">construct/copy/destruct</a></span> |
| <a class="link" href="inversive_congruential.html#id1144417-bb"><span class="identifier">inversive_congruential</span></a><span class="special">(</span><span class="identifier">IntType</span> <span class="special">=</span> <span class="number">1</span><span class="special">)</span><span class="special">;</span> |
| <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> It<span class="special">></span> <a class="link" href="inversive_congruential.html#id1144434-bb"><span class="identifier">inversive_congruential</span></a><span class="special">(</span><span class="identifier">It</span> <span class="special">&</span><span class="special">,</span> <span class="identifier">It</span><span class="special">)</span><span class="special">;</span> |
| |
| <span class="comment">// <a class="link" href="inversive_congruential.html#id1144345-bb">public member functions</a></span> |
| <span class="identifier">result_type</span> <a class="link" href="inversive_congruential.html#id1144348-bb"><span class="identifier">min</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> |
| <span class="identifier">result_type</span> <a class="link" href="inversive_congruential.html#id1144356-bb"><span class="identifier">max</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> |
| <span class="keyword">void</span> <a class="link" href="inversive_congruential.html#id1144364-bb"><span class="identifier">seed</span></a><span class="special">(</span><span class="identifier">IntType</span> <span class="special">=</span> <span class="number">1</span><span class="special">)</span><span class="special">;</span> |
| <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> It<span class="special">></span> <span class="keyword">void</span> <a class="link" href="inversive_congruential.html#id1144383-bb"><span class="identifier">seed</span></a><span class="special">(</span><span class="identifier">It</span> <span class="special">&</span><span class="special">,</span> <span class="identifier">It</span><span class="special">)</span><span class="special">;</span> |
| <span class="identifier">IntType</span> <a class="link" href="inversive_congruential.html#id1144409-bb"><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span> |
| |
| <span class="comment">// <a class="link" href="inversive_congruential.html#id1144453-bb">public static functions</a></span> |
| <span class="keyword">static</span> <span class="keyword">bool</span> <a class="link" href="inversive_congruential.html#id1144457-bb"><span class="identifier">validation</span></a><span class="special">(</span><span class="identifier">result_type</span><span class="special">)</span><span class="special">;</span> |
| <span class="keyword">static</span> <span class="keyword">const</span> <span class="keyword">bool</span> has_fixed_range<span class="special">;</span> |
| <span class="keyword">static</span> <span class="keyword">const</span> <span class="identifier">result_type</span> min_value<span class="special">;</span> |
| <span class="keyword">static</span> <span class="keyword">const</span> <span class="identifier">result_type</span> max_value<span class="special">;</span> |
| <span class="keyword">static</span> <span class="keyword">const</span> <span class="identifier">result_type</span> multiplier<span class="special">;</span> |
| <span class="keyword">static</span> <span class="keyword">const</span> <span class="identifier">result_type</span> increment<span class="special">;</span> |
| <span class="keyword">static</span> <span class="keyword">const</span> <span class="identifier">result_type</span> modulus<span class="special">;</span> |
| <span class="special">}</span><span class="special">;</span></pre></div> |
| <div class="refsect1"> |
| <a name="id2486282"></a><h2>Description</h2> |
| <p>Instantiations of class template <code class="computeroutput">inversive_congruential</code> model a <a class="link" href="../../boost_random/reference.html#boost_random.reference.concepts.pseudo_random_number_generator" title="Pseudo-Random Number Generator">pseudo-random number generator</a> . It uses the inversive congruential algorithm (ICG) described in</p> |
| <p> </p> |
| <div class="blockquote"><blockquote class="blockquote"><p> "Inversive pseudorandom number generators: concepts, results and links", Peter Hellekalek, In: "Proceedings of the 1995 Winter Simulation Conference", C. Alexopoulos, K. Kang, W.R. Lilegdon, and D. Goldsman (editors), 1995, pp. 255-262. <a href="ftp://random.mat.sbg.ac.at/pub/data/wsc95.ps" target="_top">ftp://random.mat.sbg.ac.at/pub/data/wsc95.ps</a> </p></blockquote></div> |
| <p> </p> |
| <p>The output sequence is defined by x(n+1) = (a*inv(x(n)) - b) (mod p), where x(0), a, b, and the prime number p are parameters of the generator. The expression inv(k) denotes the multiplicative inverse of k in the field of integer numbers modulo p, with inv(0) := 0.</p> |
| <p>The template parameter IntType shall denote a signed integral type large enough to hold p; a, b, and p are the parameters of the generators. The template parameter val is the validation value checked by validation.</p> |
| <p> </p> |
| <div class="note"><table border="0" summary="Note"> |
| <tr> |
| <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../doc/src/images/note.png"></td> |
| <th align="left">Note</th> |
| </tr> |
| <tr><td align="left" valign="top"><p> The implementation currently uses the Euclidian Algorithm to compute the multiplicative inverse. Therefore, the inversive generators are about 10-20 times slower than the others (see section"performance"). However, the paper talks of only 3x slowdown, so the Euclidian Algorithm is probably not optimal for calculating the multiplicative inverse. </p></td></tr> |
| </table></div> |
| <p> </p> |
| <div class="refsect2"> |
| <a name="id2486346"></a><h3> |
| <a name="boost.random.inversive_congruentialconstruct-copy-destruct"></a><code class="computeroutput">inversive_congruential</code> |
| public |
| construct/copy/destruct</h3> |
| <div class="orderedlist"><ol class="orderedlist" type="1"> |
| <li class="listitem"> |
| <pre class="literallayout"><a name="id1144417-bb"></a><span class="identifier">inversive_congruential</span><span class="special">(</span><span class="identifier">IntType</span> y0 <span class="special">=</span> <span class="number">1</span><span class="special">)</span><span class="special">;</span></pre> |
| <p>Constructs an inversive_congruential generator with <code class="computeroutput">y0</code> as the initial state. </p> |
| </li> |
| <li class="listitem"><pre class="literallayout"><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> It<span class="special">></span> <a name="id1144434-bb"></a><span class="identifier">inversive_congruential</span><span class="special">(</span><span class="identifier">It</span> <span class="special">&</span> first<span class="special">,</span> <span class="identifier">It</span> last<span class="special">)</span><span class="special">;</span></pre></li> |
| </ol></div> |
| </div> |
| <div class="refsect2"> |
| <a name="id2486492"></a><h3> |
| <a name="id1144345-bb"></a><code class="computeroutput">inversive_congruential</code> public member functions</h3> |
| <div class="orderedlist"><ol class="orderedlist" type="1"> |
| <li class="listitem"><pre class="literallayout"><span class="identifier">result_type</span> <a name="id1144348-bb"></a><span class="identifier">min</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre></li> |
| <li class="listitem"><pre class="literallayout"><span class="identifier">result_type</span> <a name="id1144356-bb"></a><span class="identifier">max</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre></li> |
| <li class="listitem"> |
| <pre class="literallayout"><span class="keyword">void</span> <a name="id1144364-bb"></a><span class="identifier">seed</span><span class="special">(</span><span class="identifier">IntType</span> y0 <span class="special">=</span> <span class="number">1</span><span class="special">)</span><span class="special">;</span></pre> |
| <p>Changes the current state to y0. </p> |
| </li> |
| <li class="listitem"><pre class="literallayout"><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> It<span class="special">></span> <span class="keyword">void</span> <a name="id1144383-bb"></a><span class="identifier">seed</span><span class="special">(</span><span class="identifier">It</span> <span class="special">&</span> first<span class="special">,</span> <span class="identifier">It</span> last<span class="special">)</span><span class="special">;</span></pre></li> |
| <li class="listitem"><pre class="literallayout"><span class="identifier">IntType</span> <a name="id1144409-bb"></a><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><span class="special">)</span><span class="special">;</span></pre></li> |
| </ol></div> |
| </div> |
| <div class="refsect2"> |
| <a name="id2486763"></a><h3> |
| <a name="id1144453-bb"></a><code class="computeroutput">inversive_congruential</code> public static functions</h3> |
| <div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><pre class="literallayout"><span class="keyword">static</span> <span class="keyword">bool</span> <a name="id1144457-bb"></a><span class="identifier">validation</span><span class="special">(</span><span class="identifier">result_type</span> x<span class="special">)</span><span class="special">;</span></pre></li></ol></div> |
| </div> |
| </div> |
| </div> |
| <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> |
| <td align="left"></td> |
| <td align="right"><div class="copyright-footer">Copyright © 2000 -2005 Jens Maurer, 2009 Steven Watanabe<p> |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) |
| </p> |
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