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   4 <title>Class template variate_generator</title>
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  24 </div>
  25 <div class="refentry">
  26 <a name="boost.variate_generator"></a><div class="titlepage"></div>
  27 <div class="refnamediv">
  28 <h2><span class="refentrytitle">Class template variate_generator</span></h2>
  29 <p>boost::variate_generator</p>
  30 </div>
  31 <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
  32 <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: &lt;<a class="link" href="../boost_random/reference.html#header.boost.random.variate_generator_hpp" title="Header &lt;boost/random/variate_generator.hpp&gt;">boost/random/variate_generator.hpp</a>&gt;
  33
  34 </span><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> Engine<span class="special">,</span> <span class="keyword">typename</span> Distribution<span class="special">&gt;</span>
  35 <span class="keyword">class</span> <a class="link" href="variate_generator.html" title="Class template variate_generator">variate_generator</a> <span class="special">{</span>
  36 <span class="keyword">public</span><span class="special">:</span>
  37   <span class="comment">// types</span>
  38   <span class="keyword">typedef</span> <span class="identifier">helper_type</span><span class="special">::</span><span class="identifier">value_type</span>   <a name="boost.variate_generator.engine_value_type"></a><span class="identifier">engine_value_type</span><span class="special">;</span>
  39   <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>
  40   <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>
  41   <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>
  42
  43   <span class="comment">// <a class="link" href="variate_generator.html#boost.variate_generatorconstruct-copy-destruct">construct/copy/destruct</a></span>
  44   <a class="link" href="variate_generator.html#id1294689-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>
  45
  46   <span class="comment">// <a class="link" href="variate_generator.html#id1294564-bb">public member functions</a></span>
  47   <span class="identifier">result_type</span> <a class="link" href="variate_generator.html#id1294568-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>
  48   <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> T<span class="special">&gt;</span> <span class="identifier">result_type</span> <a class="link" href="variate_generator.html#id1294579-bb"><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span></a><span class="special">(</span><span class="keyword">const</span> <span class="identifier">T</span> <span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
  49   <span class="identifier">engine_value_type</span> <span class="special">&amp;</span> <a class="link" href="variate_generator.html#id1294604-bb"><span class="identifier">engine</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span>
  50   <span class="keyword">const</span> <span class="identifier">engine_value_type</span> <span class="special">&amp;</span> <a class="link" href="variate_generator.html#id1294616-bb"><span class="identifier">engine</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  51   <span class="identifier">distribution_type</span> <span class="special">&amp;</span> <a class="link" href="variate_generator.html#id1294629-bb"><span class="identifier">distribution</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span>
  52   <span class="keyword">const</span> <span class="identifier">distribution_type</span> <span class="special">&amp;</span> <a class="link" href="variate_generator.html#id1294648-bb"><span class="identifier">distribution</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  53   <span class="identifier">result_type</span> <a class="link" href="variate_generator.html#id1294660-bb"><span class="identifier">min</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  54   <span class="identifier">result_type</span> <a class="link" href="variate_generator.html#id1294674-bb"><span class="identifier">max</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  55 <span class="special">}</span><span class="special">;</span></pre></div>
  56 <div class="refsect1">
  57 <a name="id3139915"></a><h2>Description</h2>
  58 <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>
  59 <p>The argument for the template parameter Engine shall be of the form U, U&amp;, 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>
  60 <p>Specializations of <code class="computeroutput"><a class="link" href="variate_generator.html" title="Class template variate_generator">variate_generator</a></code> satisfy the requirements of CopyConstructible. They also satisfy the requirements of Assignable unless the template parameter Engine is of the form U&amp;.</p>
  61 <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>
  62 <div class="refsect2">
  63 <a name="id3139977"></a><h3>
  64 <a name="boost.variate_generatorconstruct-copy-destruct"></a><code class="computeroutput">variate_generator</code>
  65         public
  66        construct/copy/destruct</h3>
  67 <div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
  68 <pre class="literallayout"><a name="id1294689-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>
  69 <p>Constructs a <code class="computeroutput"><code class="computeroutput"><a class="link" href="variate_generator.html" title="Class template variate_generator">variate_generator</a></code></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>
  70 <p>Throws: If and what the copy constructor of Engine or Distribution throws. </p>
  71 </li></ol></div>
  72 </div>
  73 <div class="refsect2">
  74 <a name="id3140081"></a><h3>
  75 <a name="id1294564-bb"></a><code class="computeroutput">variate_generator</code> public member functions</h3>
  76 <div class="orderedlist"><ol class="orderedlist" type="1">
  77 <li class="listitem">
  78 <pre class="literallayout"><span class="identifier">result_type</span> <a name="id1294568-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>
  79 <p>Returns: distribution()(engine()) </p>
  80 </li>
  81 <li class="listitem">
  82 <pre class="literallayout"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> T<span class="special">&gt;</span> <span class="identifier">result_type</span> <a name="id1294579-bb"></a><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">T</span> <span class="special">&amp;</span> value<span class="special">)</span><span class="special">;</span></pre>
  83 <p>Returns: distribution()(engine(), value). </p>
  84 </li>
  85 <li class="listitem">
  86 <pre class="literallayout"><span class="identifier">engine_value_type</span> <span class="special">&amp;</span> <a name="id1294604-bb"></a><span class="identifier">engine</span><span class="special">(</span><span class="special">)</span><span class="special">;</span></pre>
  87 <p>Returns: A reference to the associated uniform random number generator. </p>
  88 </li>
  89 <li class="listitem">
  90 <pre class="literallayout"><span class="keyword">const</span> <span class="identifier">engine_value_type</span> <span class="special">&amp;</span> <a name="id1294616-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>
  91 <p>Returns: A reference to the associated uniform random number generator. </p>
  92 </li>
  93 <li class="listitem">
  94 <pre class="literallayout"><span class="identifier">distribution_type</span> <span class="special">&amp;</span> <a name="id1294629-bb"></a><span class="identifier">distribution</span><span class="special">(</span><span class="special">)</span><span class="special">;</span></pre>
  95 <p>Returns: A reference to the associated  <a class="link" href="../boost_random/reference.html#boost_random.reference.concepts.random_distribution" title="Random Distribution">random distribution</a> . </p>
  96 </li>
  97 <li class="listitem">
  98 <pre class="literallayout"><span class="keyword">const</span> <span class="identifier">distribution_type</span> <span class="special">&amp;</span> <a name="id1294648-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>
  99 <p>Returns: A reference to the associated random distribution. </p>
 100 </li>
 101 <li class="listitem">
 102 <pre class="literallayout"><span class="identifier">result_type</span> <a name="id1294660-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>
 103 <p>Precondition: distribution().min() is well-formed</p>
 104 <p>Returns: distribution().min() </p>
 105 </li>
 106 <li class="listitem">
 107 <pre class="literallayout"><span class="identifier">result_type</span> <a name="id1294674-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>
 108 <p>Precondition: distribution().max() is well-formed</p>
 109 <p>Returns: distribution().max() </p>
 110 </li>
 111 </ol></div>
 112 </div>
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