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| <a name="boost.variate_generator"></a><div class="titlepage"></div> |
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| <h2><span class="refentrytitle">Class template variate_generator</span></h2> |
| <p>boost::variate_generator</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.variate_generator_hpp" title="Header <boost/random/variate_generator.hpp>">boost/random/variate_generator.hpp</a>> |
| |
| </span><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> Engine<span class="special">,</span> <span class="keyword">typename</span> Distribution<span class="special">></span> |
| <span class="keyword">class</span> <a class="link" href="variate_generator.html" title="Class template variate_generator">variate_generator</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">decorated_engine</span><span class="special">::</span><span class="identifier">base_type</span> <a name="boost.variate_generator.engine_value_type"></a><span class="identifier">engine_value_type</span><span class="special">;</span> |
| <span class="keyword">typedef</span> <span class="identifier">Engine</span> <a name="boost.variate_generator.engine_type"></a><span class="identifier">engine_type</span><span class="special">;</span> |
| <span class="keyword">typedef</span> <span class="identifier">Distribution</span> <a name="boost.variate_generator.distribution_type"></a><span class="identifier">distribution_type</span><span class="special">;</span> |
| <span class="keyword">typedef</span> <span class="identifier">Distribution</span><span class="special">::</span><span class="identifier">result_type</span> <a name="boost.variate_generator.result_type"></a><span class="identifier">result_type</span><span class="special">;</span> |
| |
| <span class="comment">// <a class="link" href="variate_generator.html#boost.variate_generatorconstruct-copy-destruct">construct/copy/destruct</a></span> |
| <a class="link" href="variate_generator.html#id1150156-bb"><span class="identifier">variate_generator</span></a><span class="special">(</span><span class="identifier">Engine</span><span class="special">,</span> <span class="identifier">Distribution</span><span class="special">)</span><span class="special">;</span> |
| |
| <span class="comment">// <a class="link" href="variate_generator.html#id1149945-bb">public member functions</a></span> |
| <span class="identifier">result_type</span> <a class="link" href="variate_generator.html#id1149949-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="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> T<span class="special">></span> <span class="identifier">result_type</span> <a class="link" href="variate_generator.html#id1150052-bb"><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span></a><span class="special">(</span><span class="identifier">T</span><span class="special">)</span><span class="special">;</span> |
| <span class="identifier">engine_value_type</span> <span class="special">&</span> <a class="link" href="variate_generator.html#id1150077-bb"><span class="identifier">engine</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span> |
| <span class="keyword">const</span> <span class="identifier">engine_value_type</span> <span class="special">&</span> <a class="link" href="variate_generator.html#id1150090-bb"><span class="identifier">engine</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> |
| <span class="identifier">distribution_type</span> <span class="special">&</span> <a class="link" href="variate_generator.html#id1150102-bb"><span class="identifier">distribution</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span> |
| <span class="keyword">const</span> <span class="identifier">distribution_type</span> <span class="special">&</span> <a class="link" href="variate_generator.html#id1150115-bb"><span class="identifier">distribution</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="variate_generator.html#id1150127-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="variate_generator.html#id1150142-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="special">}</span><span class="special">;</span></pre></div> |
| <div class="refsect1"> |
| <a name="id2516612"></a><h2>Description</h2> |
| <p>A random variate generator is used to join a random number generator together with a random number distribution. Boost.Random provides a vast choice of <a class="link" href="../boost_random/reference.html#boost_random.reference.generators" title="Generators">generators</a> as well as <a class="link" href="../boost_random/reference.html#boost_random.reference.distributions" title="Distributions">distributions</a> .</p> |
| <p>Instantations of class template <code class="computeroutput">variate_generator</code> model a <a class="link" href="../boost_random/reference.html#boost_random.reference.concepts.number_generator" title="Number Generator">number generator</a> .</p> |
| <p>The argument for the template parameter Engine shall be of the form U, U&, or U*, where U models a <a class="link" href="../boost_random/reference.html#boost_random.reference.concepts.uniform_random_number_generator" title="Uniform Random Number Generator">uniform random number generator</a> . Then, the member engine_value_type names U (not the pointer or reference to U).</p> |
| <p>Specializations of <code class="computeroutput">variate_generator</code> satisfy the requirements of CopyConstructible. They also satisfy the requirements of Assignable unless the template parameter Engine is of the form U&.</p> |
| <p>The complexity of all functions specified in this section is constant. No function described in this section except the constructor throws an exception. </p> |
| <div class="refsect2"> |
| <a name="id2516687"></a><h3> |
| <a name="boost.variate_generatorconstruct-copy-destruct"></a><code class="computeroutput">variate_generator</code> |
| public |
| construct/copy/destruct</h3> |
| <div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"> |
| <pre class="literallayout"><a name="id1150156-bb"></a><span class="identifier">variate_generator</span><span class="special">(</span><span class="identifier">Engine</span> e<span class="special">,</span> <span class="identifier">Distribution</span> d<span class="special">)</span><span class="special">;</span></pre> |
| <p>Constructs a <code class="computeroutput">variate_generator</code> object with the associated <a class="link" href="../boost_random/reference.html#boost_random.reference.concepts.uniform_random_number_generator" title="Uniform Random Number Generator">uniform random number generator</a> eng and the associated <a class="link" href="../boost_random/reference.html#boost_random.reference.concepts.random_distribution" title="Random Distribution">random distribution</a> d.</p> |
| <p>Throws: If and what the copy constructor of Engine or Distribution throws. </p> |
| </li></ol></div> |
| </div> |
| <div class="refsect2"> |
| <a name="id2516783"></a><h3> |
| <a name="id1149945-bb"></a><code class="computeroutput">variate_generator</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="id1149949-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> |
| <p>Returns: distribution()(e)</p> |
| <p>Notes: The sequence of numbers produced by the <a class="link" href="../boost_random/reference.html#boost_random.reference.concepts.uniform_random_number_generator" title="Uniform Random Number Generator">uniform random number generator</a> e, s<sub>e</sub>, is obtained from the sequence of numbers produced by the associated <a class="link" href="../boost_random/reference.html#boost_random.reference.concepts.uniform_random_number_generator" title="Uniform Random Number Generator">uniform random number generator</a> eng, s<sub>eng</sub>, as follows: Consider the values of <code class="computeroutput">numeric_limits<T>::is_integer</code> for <code class="computeroutput">T</code> both <code class="computeroutput">Distribution::input_type</code> and <code class="computeroutput">engine_value_type::result_type</code>. If the values for both types are true, then se is identical to s<sub>eng</sub>. Otherwise, if the values for both types are false, then the numbers in s<sub>eng</sub> are divided by engine().max()-engine().min() to obtain the numbers in s<sub>e</sub>. Otherwise, if the value for <code class="computeroutput">engine_value_type::result_type</code> is true and the value for <code class="computeroutput">Distribution::input_type</code> is false, then the numbers in s<sub>eng</sub> are divided by engine().max()-engine().min()+1 to obtain the numbers in s<sub>e</sub>. Otherwise, the mapping from s<sub>eng</sub> to s<sub>e</sub> is implementation-defined. In all cases, an implicit conversion from <code class="computeroutput">engine_value_type::result_type</code> to <code class="computeroutput">Distribution::input_type</code> is performed. If such a conversion does not exist, the program is ill-formed. </p> |
| </li> |
| <li class="listitem"> |
| <pre class="literallayout"><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> T<span class="special">></span> <span class="identifier">result_type</span> <a name="id1150052-bb"></a><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><span class="identifier">T</span> value<span class="special">)</span><span class="special">;</span></pre> |
| <p>Returns: distribution()(e, value). For the semantics of e, see the description of operator()(). </p> |
| </li> |
| <li class="listitem"> |
| <pre class="literallayout"><span class="identifier">engine_value_type</span> <span class="special">&</span> <a name="id1150077-bb"></a><span class="identifier">engine</span><span class="special">(</span><span class="special">)</span><span class="special">;</span></pre> |
| <p>Returns: A reference to the associated uniform random number generator. </p> |
| </li> |
| <li class="listitem"> |
| <pre class="literallayout"><span class="keyword">const</span> <span class="identifier">engine_value_type</span> <span class="special">&</span> <a name="id1150090-bb"></a><span class="identifier">engine</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre> |
| <p>Returns: A reference to the associated uniform random number generator. </p> |
| </li> |
| <li class="listitem"> |
| <pre class="literallayout"><span class="identifier">distribution_type</span> <span class="special">&</span> <a name="id1150102-bb"></a><span class="identifier">distribution</span><span class="special">(</span><span class="special">)</span><span class="special">;</span></pre> |
| <p>Returns: A reference to the associated random distribution. </p> |
| </li> |
| <li class="listitem"> |
| <pre class="literallayout"><span class="keyword">const</span> <span class="identifier">distribution_type</span> <span class="special">&</span> <a name="id1150115-bb"></a><span class="identifier">distribution</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre> |
| <p>Returns: A reference to the associated random distribution. </p> |
| </li> |
| <li class="listitem"> |
| <pre class="literallayout"><span class="identifier">result_type</span> <a name="id1150127-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> |
| <p>Precondition: distribution().min() is well-formed</p> |
| <p>Returns: distribution().min() </p> |
| </li> |
| <li class="listitem"> |
| <pre class="literallayout"><span class="identifier">result_type</span> <a name="id1150142-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> |
| <p>Precondition: distribution().max() is well-formed</p> |
| <p>Returns: distribution().max() </p> |
| </li> |
| </ol></div> |
| </div> |
| </div> |
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| <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>) |
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