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<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="random/bernoulli_distribution.html" title="cpp/numeric/random/bernoulli distribution"><span class="t-lines"><span>bernoulli_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="random/binomial_distribution.html" title="cpp/numeric/random/binomial distribution"><span class="t-lines"><span>binomial_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="random/negative_binomial_distribution.html" title="cpp/numeric/random/negative binomial distribution"><span class="t-lines"><span>negative_binomial_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="random/geometric_distribution.html" title="cpp/numeric/random/geometric distribution"><span class="t-lines"><span>geometric_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv-h2"><td colspan="5"> Poisson distributions</td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="random/poisson_distribution.html" title="cpp/numeric/random/poisson distribution"><span class="t-lines"><span>poisson_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="random/exponential_distribution.html" title="cpp/numeric/random/exponential distribution"><span class="t-lines"><span>exponential_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="random/gamma_distribution.html" title="cpp/numeric/random/gamma distribution"><span class="t-lines"><span>gamma_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="random/weibull_distribution.html" title="cpp/numeric/random/weibull distribution"><span class="t-lines"><span>weibull_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="random/extreme_value_distribution.html" title="cpp/numeric/random/extreme value distribution"><span class="t-lines"><span>extreme_value_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv-h2"><td colspan="5"> Normal distributions</td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="random/normal_distribution.html" title="cpp/numeric/random/normal distribution"><span class="t-lines"><span>normal_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="random/lognormal_distribution.html" title="cpp/numeric/random/lognormal distribution"><span class="t-lines"><span>lognormal_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="random/chi_squared_distribution.html" title="cpp/numeric/random/chi squared distribution"><span class="t-lines"><span>chi_squared_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="random/cauchy_distribution.html" title="cpp/numeric/random/cauchy distribution"><span class="t-lines"><span>cauchy_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="random/fisher_f_distribution.html" title="cpp/numeric/random/fisher f distribution"><span class="t-lines"><span>fisher_f_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="random/student_t_distribution.html" title="cpp/numeric/random/student t distribution"><span class="t-lines"><span>student_t_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv-h2"><td colspan="5"> Sampling distributions</td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="random/discrete_distribution.html" title="cpp/numeric/random/discrete distribution"><span class="t-lines"><span>discrete_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="random/piecewise_constant_distribution.html" title="cpp/numeric/random/piecewise constant distribution"><span class="t-lines"><span>piecewise_constant_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="random/piecewise_linear_distribution.html" title="cpp/numeric/random/piecewise linear distribution"><span class="t-lines"><span>piecewise_linear_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv-h1"><td colspan="5"> Seed Sequences</td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="random/seed_seq.html" title="cpp/numeric/random/seed seq"><span class="t-lines"><span>seed_seq</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv-h1"><td colspan="5"> C library</td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="random/rand.html" title="cpp/numeric/random/rand"><span class="t-lines"><span>rand</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="random/srand.html" title="cpp/numeric/random/srand"><span class="t-lines"><span>srand</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="random/RAND_MAX.html" title="cpp/numeric/random/RAND MAX"><span class="t-lines"><span>RAND_MAX</span></span></a></div></div></td></tr>
</table></div><div><span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/numeric/random/navbar_content&amp;action=edit">&#91;edit&#93;</a></span></div></div></div></div><div class="t-navbar-sep">&#160;</div></div>
<p>The random number library provides classes that generate random and pseudo-random numbers.  These classes include:
</p>
<ul><li> Random number engines (both pseudo-random number generators, which generate integer sequences with a uniform distribution, and true random number generators if available) 
</li><li> Random number distributions (e.g. <a href="random/uniform_int_distribution.html" title="cpp/numeric/random/uniform int distribution">uniform</a>, <a href="random/normal_distribution.html" title="cpp/numeric/random/normal distribution">normal</a>, or <a href="random/poisson_distribution.html" title="cpp/numeric/random/poisson distribution">poisson distributions</a>) which convert the output of random number engines into various statistical distributions 
</li></ul>
<p>Engines and distributions are designed to be used together to produce random values. All of the engines may be specifically seeded, serialized, and deserialized for use with repeatable simulators.
</p>
<table id="toc" class="toc"><tr><td><div id="toctitle"><h2>Contents</h2></div>
<ul>
<li class="toclevel-1 tocsection-1"><a href="random.html#Random_number_engines"><span class="tocnumber">1</span> <span class="toctext">Random number engines</span></a>
<ul>
<li class="toclevel-2 tocsection-2"><a href="random.html#Random_number_engine_adaptors"><span class="tocnumber">1.1</span> <span class="toctext">Random number engine adaptors</span></a></li>
<li class="toclevel-2 tocsection-3"><a href="random.html#Predefined_random_number_generators"><span class="tocnumber">1.2</span> <span class="toctext">Predefined random number generators</span></a></li>
<li class="toclevel-2 tocsection-4"><a href="random.html#Non-deterministic_random_numbers"><span class="tocnumber">1.3</span> <span class="toctext">Non-deterministic random numbers</span></a></li>
</ul>
</li>
<li class="toclevel-1 tocsection-5"><a href="random.html#Random_number_distributions"><span class="tocnumber">2</span> <span class="toctext">Random number distributions</span></a>
<ul>
<li class="toclevel-2"><a href="random.html#Uniform_distributions"><span class="tocnumber">2.1</span> <span class="toctext">Uniform distributions</span></a></li>
<li class="toclevel-2"><a href="random.html#Bernoulli_distributions"><span class="tocnumber">2.2</span> <span class="toctext">Bernoulli distributions</span></a></li>
<li class="toclevel-2"><a href="random.html#Poisson_distributions"><span class="tocnumber">2.3</span> <span class="toctext">Poisson distributions</span></a></li>
<li class="toclevel-2"><a href="random.html#Normal_distributions"><span class="tocnumber">2.4</span> <span class="toctext">Normal distributions</span></a></li>
<li class="toclevel-2"><a href="random.html#Sampling_distributions"><span class="tocnumber">2.5</span> <span class="toctext">Sampling distributions</span></a></li>
</ul>
</li>
<li class="toclevel-1 tocsection-6"><a href="random.html#Utilities"><span class="tocnumber">3</span> <span class="toctext">Utilities</span></a></li>
<li class="toclevel-1 tocsection-7"><a href="random.html#C_random_library"><span class="tocnumber">4</span> <span class="toctext">C random library</span></a></li>
<li class="toclevel-1 tocsection-8"><a href="random.html#Example"><span class="tocnumber">5</span> <span class="toctext">Example</span></a></li>
<li class="toclevel-1 tocsection-9"><a href="random.html#See_also"><span class="tocnumber">6</span> <span class="toctext">See also</span></a></li>
</ul>
</td></tr></table>
<h3><span class="editsection">[<a href="http://en.cppreference.com/mwiki/index.php?title=cpp/numeric/random&amp;action=edit&amp;section=1" title="Edit section: Random number engines">edit</a>]</span> <span class="mw-headline" id="Random_number_engines">Random number engines</span></h3>
<p>Random number engines generate pseudo-random numbers using seed data as entropy source. Several different classes of pseudo-random number generation algorithms are implemented as templates that can be customized.
</p><p>The choice of which engine to use involves a number of tradeoffs:  the linear congruential engine is moderately fast and has a very small storage requirement for state.  The lagged Fibonacci generators are very fast even on processors without advanced arithmetic instruction sets, at the expense of greater state storage and sometimes less desirable spectral characteristics.  The Mersenne twister is slower and has greater state storage requirements but with the right parameters has the longest non-repeating sequence with the most desirable spectral characteristics (for a given definition of desirable).
</p>
<table class="t-dsc-begin">

<tr class="t-dsc-header">
<td colspan="2"> <div>Defined in header <code>&lt;random&gt;</code> </div>
</td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/linear_congruential_engine.html" title="cpp/numeric/random/linear congruential engine"> <span class="t-lines"><span>linear_congruential_engine</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   implements <a href="http://en.wikipedia.com/wiki/Linear_congruential_generator" class="extiw" title="enwiki:Linear congruential generator"> linear congruential</a> algorithm  <br /> <span class="t-mark">(class template)</span>
</td></tr>


<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/mersenne_twister_engine.html" title="cpp/numeric/random/mersenne twister engine"> <span class="t-lines"><span>mersenne_twister_engine</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   implements <a href="http://en.wikipedia.com/wiki/Mersenne_twister" class="extiw" title="enwiki:Mersenne twister"> Mersenne twister</a> algorithm  <br /> <span class="t-mark">(class template)</span>
</td></tr>


<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/subtract_with_carry_engine.html" title="cpp/numeric/random/subtract with carry engine"> <span class="t-lines"><span>subtract_with_carry_engine</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   implements subtract with carry (a <a href="http://en.wikipedia.com/wiki/Lagged_Fibonacci_generator" class="extiw" title="enwiki:Lagged Fibonacci generator"> lagged Fibonacci</a>) algorithm  <br /> <span class="t-mark">(class template)</span>
</td></tr>

</table>
<h4><span class="editsection">[<a href="http://en.cppreference.com/mwiki/index.php?title=cpp/numeric/random&amp;action=edit&amp;section=2" title="Edit section: Random number engine adaptors">edit</a>]</span> <span class="mw-headline" id="Random_number_engine_adaptors">Random number engine adaptors</span></h4>
<p>Random number engine adaptors generate pseudo-random numbers using another random number engine as entropy source.  They are generally used to alter the spectral characteristics of the underlying engine.
</p>
<table class="t-dsc-begin">

<tr class="t-dsc-header">
<td colspan="2"> <div>Defined in header <code>&lt;random&gt;</code> </div>
</td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/discard_block_engine.html" title="cpp/numeric/random/discard block engine"> <span class="t-lines"><span>discard_block_engine</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   discards some output of a random number engine  <br /> <span class="t-mark">(class template)</span>
</td></tr>


<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/independent_bits_engine.html" title="cpp/numeric/random/independent bits engine"> <span class="t-lines"><span>independent_bits_engine</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   packs the output of a random number engine into blocks of specified number of bits  <br /> <span class="t-mark">(class template)</span>
</td></tr>


<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/shuffle_order_engine.html" title="cpp/numeric/random/shuffle order engine"> <span class="t-lines"><span>shuffle_order_engine</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   delivers the output of a random number engine in different order  <br /> <span class="t-mark">(class template)</span>
</td></tr>

</table>
<h4><span class="editsection">[<a href="http://en.cppreference.com/mwiki/index.php?title=cpp/numeric/random&amp;action=edit&amp;section=3" title="Edit section: Predefined random number generators">edit</a>]</span> <span class="mw-headline" id="Predefined_random_number_generators">Predefined random number generators</span></h4>
<p>Several specific popular algorithms are predefined.
</p>
<table class="t-dsc-begin">

<tr class="t-dsc-header">
<td colspan="2"> <div>Defined in header <code>&lt;random&gt;</code> </div>
</td></tr>

<tr class="t-dsc-hitem">
<td>  Type
</td>
<td>  Definition
</td></tr>


<tr class="t-dsc">
<td>  <code>minstd_rand0</code>
</td>
<td>  <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="random/linear_congruential_engine.html"><span class="kw1228">std::<span class="me2">linear_congruential_engine</span></span></a><span class="sy1">&lt;</span><a href="../types/integer.html"><span class="kw126">std::<span class="me2">uint_fast32_t</span></span></a>, <span class="nu0">16807</span>, <span class="nu0">0</span>, <span class="nu0">2147483647</span><span class="sy1">&gt;</span></span></span><br />
<p>Discovered in 1969 by Lewis, Goodman and Miller, adopted as "Minimal standard" in 1988 by Park and Miller <span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/numeric/random/dsc_minstd_rand0&amp;action=edit">&#91;edit&#93;</a></span>
</p>
</td></tr>

<tr class="t-dsc">
<td>  <code>minstd_rand</code>
</td>
<td>  <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="random/linear_congruential_engine.html"><span class="kw1228">std::<span class="me2">linear_congruential_engine</span></span></a><span class="sy1">&lt;</span><a href="../types/integer.html"><span class="kw126">std::<span class="me2">uint_fast32_t</span></span></a>, <span class="nu0">48271</span>, <span class="nu0">0</span>, <span class="nu0">2147483647</span><span class="sy1">&gt;</span></span></span><br />
<p>Newer "Minimum standard", recommended by Park, Miller, and Stockmeyer in 1993<span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/numeric/random/dsc_minstd_rand&amp;action=edit">&#91;edit&#93;</a></span>
</p>
</td></tr>

<tr class="t-dsc">
<td>  <code>mt19937</code>
</td>
<td>
<p><span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="random/mersenne_twister_engine.html"><span class="kw1229">std::<span class="me2">mersenne_twister_engine</span></span></a><span class="sy1">&lt;</span><a href="../types/integer.html"><span class="kw126">std::<span class="me2">uint_fast32_t</span></span></a>, <span class="nu0">32</span>, <span class="nu0">624</span>, <span class="nu0">397</span>, <span class="nu0">31</span>, <br />
&#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160;<span class="nu12">0x9908b0df</span>, <span class="nu0">11</span>, <br />
&#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160;<span class="nu12">0xffffffff</span>, <span class="nu0">7</span>, <br />
&#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160;<span class="nu12">0x9d2c5680</span>, <span class="nu0">15</span>, <br />
&#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160;<span class="nu12">0xefc60000</span>, <span class="nu0">18</span>, <span class="nu0">1812433253</span><span class="sy1">&gt;</span></span></span><br />
32-bit Mersenne Twister by Matsumoto and Nishimura, 1998<span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/numeric/random/dsc_mt19937&amp;action=edit">&#91;edit&#93;</a></span>
</p>
</td></tr>

<tr class="t-dsc">
<td>  <code>mt19937_64</code>
</td>
<td>
<p><span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="random/mersenne_twister_engine.html"><span class="kw1229">std::<span class="me2">mersenne_twister_engine</span></span></a><span class="sy1">&lt;</span><a href="../types/integer.html"><span class="kw127">std::<span class="me2">uint_fast64_t</span></span></a>, <span class="nu0">64</span>, <span class="nu0">312</span>, <span class="nu0">156</span>, <span class="nu0">31</span>,<br />
&#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160;<span class="nu12">0xb5026f5aa96619e9</span>, <span class="nu0">29</span>,<br />
&#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160;<span class="nu12">0x5555555555555555</span>, <span class="nu0">17</span>,<br />
&#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160;<span class="nu12">0x71d67fffeda60000</span>, <span class="nu0">37</span>,<br />
&#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160;<span class="nu12">0xfff7eee000000000</span>, <span class="nu0">43</span>, <span class="nu0">6364136223846793005</span><span class="sy1">&gt;</span></span></span><br />
64-bit Mersenne Twister by Matsumoto and Nishimura, 2000<span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/numeric/random/dsc_mt19937_64&amp;action=edit">&#91;edit&#93;</a></span>
</p>
</td></tr>

<tr class="t-dsc">
<td>  <code>ranlux24_base</code>
</td>
<td>  <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="random/subtract_with_carry_engine.html"><span class="kw1230">std::<span class="me2">subtract_with_carry_engine</span></span></a><span class="sy1">&lt;</span><a href="../types/integer.html"><span class="kw126">std::<span class="me2">uint_fast32_t</span></span></a>, <span class="nu0">24</span>, <span class="nu0">10</span>, <span class="nu0">24</span><span class="sy1">&gt;</span></span></span><span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/numeric/random/dsc_ranlux24_base&amp;action=edit">&#91;edit&#93;</a></span>
</td></tr>

<tr class="t-dsc">
<td>  <code>ranlux48_base</code>
</td>
<td>  <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="random/subtract_with_carry_engine.html"><span class="kw1230">std::<span class="me2">subtract_with_carry_engine</span></span></a><span class="sy1">&lt;</span><a href="../types/integer.html"><span class="kw127">std::<span class="me2">uint_fast64_t</span></span></a>, <span class="nu0">48</span>, <span class="nu0">5</span>, <span class="nu0">12</span><span class="sy1">&gt;</span></span></span><span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/numeric/random/dsc_ranlux48_base&amp;action=edit">&#91;edit&#93;</a></span>
</td></tr>

<tr class="t-dsc">
<td>  <code>ranlux24</code>
</td>
<td>  <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="random/discard_block_engine.html"><span class="kw1231">std::<span class="me2">discard_block_engine</span></span></a><span class="sy1">&lt;</span><a href="random/subtract_with_carry_engine.html"><span class="kw1239">std::<span class="me2">ranlux24_base</span></span></a>, <span class="nu0">223</span>, <span class="nu0">23</span><span class="sy1">&gt;</span></span></span><br />
<p>24-bit RANLUX generator by Martin Lüscher and Fred James, 1994<span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/numeric/random/dsc_ranlux24&amp;action=edit">&#91;edit&#93;</a></span>
</p>
</td></tr>

<tr class="t-dsc">
<td>  <code>ranlux48</code>
</td>
<td>  <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="random/discard_block_engine.html"><span class="kw1231">std::<span class="me2">discard_block_engine</span></span></a><span class="sy1">&lt;</span><a href="random/subtract_with_carry_engine.html"><span class="kw1240">std::<span class="me2">ranlux48_base</span></span></a>, <span class="nu0">389</span>, <span class="nu0">11</span><span class="sy1">&gt;</span></span></span><br />
<p>48-bit RANLUX generator by Martin Lüscher and Fred James, 1994<span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/numeric/random/dsc_ranlux48&amp;action=edit">&#91;edit&#93;</a></span>
</p>
</td></tr>

<tr class="t-dsc">
<td>  <code>knuth_b</code>
</td>
<td>  <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="random/shuffle_order_engine.html"><span class="kw1233">std::<span class="me2">shuffle_order_engine</span></span></a><span class="sy1">&lt;</span><a href="random/linear_congruential_engine.html"><span class="kw1235">std::<span class="me2">minstd_rand0</span></span></a>, <span class="nu0">256</span><span class="sy1">&gt;</span></span></span><span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/numeric/random/dsc_knuth_b&amp;action=edit">&#91;edit&#93;</a></span>
</td></tr>

<tr class="t-dsc">
<td>  <code>default_random_engine</code>
</td>
<td>  <i>implementation-defined</i>
</td></tr>

</table>
<h4><span class="editsection">[<a href="http://en.cppreference.com/mwiki/index.php?title=cpp/numeric/random&amp;action=edit&amp;section=4" title="Edit section: Non-deterministic random numbers">edit</a>]</span> <span class="mw-headline" id="Non-deterministic_random_numbers">Non-deterministic random numbers</span></h4>
<p><span class="t-lc"><a href="random/random_device.html" title="cpp/numeric/random/random device">std::random_device</a></span> is a non-deterministic uniform random number generator, although implementations are allowed to implement <span class="t-lc"><a href="random/random_device.html" title="cpp/numeric/random/random device">std::random_device</a></span> using a pseudo-random number engine if there is no support for non-deterministic random number generation.
</p>
<table class="t-dsc-begin">

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/random_device.html" title="cpp/numeric/random/random device"> <span class="t-lines"><span>random_device</span></span></a></div></div>
</td>
<td>   non-deterministic random number generator using hardware entropy source  <br /> <span class="t-mark">(class)</span> <span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/numeric/random/dsc_random_device&amp;action=edit">&#91;edit&#93;</a></span>
</td></tr>
</table>
<h3><span class="editsection">[<a href="http://en.cppreference.com/mwiki/index.php?title=cpp/numeric/random&amp;action=edit&amp;section=5" title="Edit section: Random number distributions">edit</a>]</span> <span class="mw-headline" id="Random_number_distributions">Random number distributions</span></h3>
<p>A random number distribution post-processes the output of an random number engine in such a way that resulting output is distributed according to a defined statistical probability density function.
</p>
<table class="t-dsc-begin">

<tr class="t-dsc-header">
<td colspan="2"> <div>Defined in header <code>&lt;random&gt;</code> </div>
</td></tr>

<tr class="t-dsc-sep">
<td colspan="2">
</td></tr>
<tr>
<td colspan="2"> <h5> <span class="mw-headline" id="Uniform_distributions">  Uniform distributions </span></h5>
</td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/uniform_int_distribution.html" title="cpp/numeric/random/uniform int distribution"> <span class="t-lines"><span>uniform_int_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   produces integer values evenly distributed across a range  <br /> <span class="t-mark">(class template)</span> <span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/numeric/random/dsc_uniform_int_distribution&amp;action=edit">&#91;edit&#93;</a></span>
</td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/uniform_real_distribution.html" title="cpp/numeric/random/uniform real distribution"> <span class="t-lines"><span>uniform_real_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   produces real values evenly distributed across a range  <br /> <span class="t-mark">(class template)</span> <span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/numeric/random/dsc_uniform_real_distribution&amp;action=edit">&#91;edit&#93;</a></span>
</td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/generate_canonical.html" title="cpp/numeric/random/generate canonical"> <span class="t-lines"><span>generate_canonical</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   evenly distributes real values of given precision across [0, 1)  <br /> <span class="t-mark">(function template)</span> <span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/numeric/random/dsc_generate_canonical&amp;action=edit">&#91;edit&#93;</a></span>
</td></tr>


<tr>
<td colspan="2"> <h5> <span class="mw-headline" id="Bernoulli_distributions">  Bernoulli distributions </span></h5>
</td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/bernoulli_distribution.html" title="cpp/numeric/random/bernoulli distribution"> <span class="t-lines"><span>bernoulli_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   produces <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span></span></span> values on a <a href="http://en.wikipedia.com/wiki/Bernoulli_distribution" class="extiw" title="enwiki:Bernoulli distribution"> Bernoulli distribution</a>.  <br /> <span class="t-mark">(class)</span>
</td></tr>


<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/binomial_distribution.html" title="cpp/numeric/random/binomial distribution"> <span class="t-lines"><span>binomial_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   produces integer values on a  <a href="http://en.wikipedia.com/wiki/Binomial_distribution" class="extiw" title="enwiki:Binomial distribution"> binomial distribution</a>.   <br /> <span class="t-mark">(class template)</span>
</td></tr>


<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/negative_binomial_distribution.html" title="cpp/numeric/random/negative binomial distribution"> <span class="t-lines"><span>negative_binomial_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   produces integer values on a  <a href="http://en.wikipedia.com/wiki/Negative_binomial_distribution" class="extiw" title="enwiki:Negative binomial distribution"> negative binomial distribution</a>.   <br /> <span class="t-mark">(class template)</span>
</td></tr>


<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/geometric_distribution.html" title="cpp/numeric/random/geometric distribution"> <span class="t-lines"><span>geometric_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   produces integer values on a  <a href="http://en.wikipedia.com/wiki/Geometric_distribution" class="extiw" title="enwiki:Geometric distribution"> geometric distribution</a>.   <br /> <span class="t-mark">(class template)</span>
</td></tr>



<tr>
<td colspan="2"> <h5> <span class="mw-headline" id="Poisson_distributions">  Poisson distributions </span></h5>
</td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/poisson_distribution.html" title="cpp/numeric/random/poisson distribution"> <span class="t-lines"><span>poisson_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   produces integer values on a  <a href="http://en.wikipedia.com/wiki/Poisson_distribution" class="extiw" title="enwiki:Poisson distribution"> poisson distribution</a>.  <br /> <span class="t-mark">(class template)</span>
</td></tr>


<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/exponential_distribution.html" title="cpp/numeric/random/exponential distribution"> <span class="t-lines"><span>exponential_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   produces real values on an  <a href="http://en.wikipedia.com/wiki/Exponential_distribution" class="extiw" title="enwiki:Exponential distribution"> exponential distribution</a>.  <br /> <span class="t-mark">(class template)</span>
</td></tr>


<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/gamma_distribution.html" title="cpp/numeric/random/gamma distribution"> <span class="t-lines"><span>gamma_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   produces real values on an  <a href="http://en.wikipedia.com/wiki/Gamma_distribution" class="extiw" title="enwiki:Gamma distribution"> gamma distribution</a>.  <br /> <span class="t-mark">(class template)</span>
</td></tr>


<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/weibull_distribution.html" title="cpp/numeric/random/weibull distribution"> <span class="t-lines"><span>weibull_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>  produces real values on a  <a href="http://en.wikipedia.com/wiki/Weibull_distribution" class="extiw" title="enwiki:Weibull distribution"> Weibull distribution</a>.  <br /> <span class="t-mark">(class template)</span>
</td></tr>


<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/extreme_value_distribution.html" title="cpp/numeric/random/extreme value distribution"> <span class="t-lines"><span>extreme_value_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   produces real values on an  <a href="http://en.wikipedia.com/wiki/Generalized_extreme_value_distribution" class="extiw" title="enwiki:Generalized extreme value distribution"> extreme value distribution</a>.  <br /> <span class="t-mark">(class template)</span>
</td></tr>



<tr>
<td colspan="2"> <h5> <span class="mw-headline" id="Normal_distributions">  Normal distributions </span></h5>
</td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/normal_distribution.html" title="cpp/numeric/random/normal distribution"> <span class="t-lines"><span>normal_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   produces real values on a  <a href="http://en.wikipedia.com/wiki/Normal_distribution" class="extiw" title="enwiki:Normal distribution"> standard normal (Gaussian) distribution</a>.  <br /> <span class="t-mark">(class template)</span>
</td></tr>


<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/lognormal_distribution.html" title="cpp/numeric/random/lognormal distribution"> <span class="t-lines"><span>lognormal_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   produces real values on a  <a href="http://en.wikipedia.com/wiki/Lognormal_distribution" class="extiw" title="enwiki:Lognormal distribution"> lognormal distribution</a>.  <br /> <span class="t-mark">(class template)</span>
</td></tr>


<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/chi_squared_distribution.html" title="cpp/numeric/random/chi squared distribution"> <span class="t-lines"><span>chi_squared_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   produces real values on a  <a href="http://en.wikipedia.com/wiki/Chi-squared_distribution" class="extiw" title="enwiki:Chi-squared distribution"> chi-squared distribution</a>.   <br /> <span class="t-mark">(class template)</span>
</td></tr>


<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/cauchy_distribution.html" title="cpp/numeric/random/cauchy distribution"> <span class="t-lines"><span>cauchy_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   produces real values on a  <a href="http://en.wikipedia.com/wiki/Cauchy_distribution" class="extiw" title="enwiki:Cauchy distribution"> Cauchy distribution</a>.  <br /> <span class="t-mark">(class template)</span>
</td></tr>


<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/fisher_f_distribution.html" title="cpp/numeric/random/fisher f distribution"> <span class="t-lines"><span>fisher_f_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   produces real values on a  <a href="http://en.wikipedia.com/wiki/F-distribution" class="extiw" title="enwiki:F-distribution"> Fisher's F-distribution</a>.  <br /> <span class="t-mark">(class template)</span>
</td></tr>


<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/student_t_distribution.html" title="cpp/numeric/random/student t distribution"> <span class="t-lines"><span>student_t_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   produces real values on a  <a href="http://en.wikipedia.com/wiki/Student%27s_t-distribution" class="extiw" title="enwiki:Student's t-distribution"> Student's t-distribution</a>.  <br /> <span class="t-mark">(class template)</span>
</td></tr>



<tr>
<td colspan="2"> <h5> <span class="mw-headline" id="Sampling_distributions">  Sampling distributions </span></h5>
</td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/discrete_distribution.html" title="cpp/numeric/random/discrete distribution"> <span class="t-lines"><span>discrete_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   produces random integers on a discrete distribution.  <br /> <span class="t-mark">(class template)</span>
</td></tr>


<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/piecewise_constant_distribution.html" title="cpp/numeric/random/piecewise constant distribution"> <span class="t-lines"><span>piecewise_constant_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   produces real values distributed on constant subintervals. <br /> <span class="t-mark">(class template)</span>
</td></tr>


<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/piecewise_linear_distribution.html" title="cpp/numeric/random/piecewise linear distribution"> <span class="t-lines"><span>piecewise_linear_distribution</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   produces real values distributed on defined subintervals.  <br /> <span class="t-mark">(class template)</span>
</td></tr>

</table>
<h3><span class="editsection">[<a href="http://en.cppreference.com/mwiki/index.php?title=cpp/numeric/random&amp;action=edit&amp;section=6" title="Edit section: Utilities">edit</a>]</span> <span class="mw-headline" id="Utilities">Utilities</span></h3>
<table class="t-dsc-begin">

<tr class="t-dsc-header">
<td colspan="2"> <div>Defined in header <code>&lt;random&gt;</code> </div>
</td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/seed_seq.html" title="cpp/numeric/random/seed seq"> <span class="t-lines"><span>seed_seq</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td>   general-purpose bias-eliminating scrambled seed sequence generator  <br /> <span class="t-mark">(class)</span>
</td></tr>

</table>
<h3><span class="editsection">[<a href="http://en.cppreference.com/mwiki/index.php?title=cpp/numeric/random&amp;action=edit&amp;section=7" title="Edit section: C random library">edit</a>]</span> <span class="mw-headline" id="C_random_library">C random library</span></h3>
<p>In addition to the engines and distributions described above, the functions and constants from the C random library are also available though not recommended:
</p>
<table class="t-dsc-begin">

<tr class="t-dsc-header">
<td colspan="2"> <div>Defined in header <code>&lt;cstdlib&gt;</code> </div>
</td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/rand.html" title="cpp/numeric/random/rand"> <span class="t-lines"><span>rand</span></span></a></div></div>
</td>
<td>   generates a pseudo-random number  <br /> <span class="t-mark">(function)</span> <span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/numeric/random/dsc_rand&amp;action=edit">&#91;edit&#93;</a></span>
</td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/srand.html" title="cpp/numeric/random/srand"> <span class="t-lines"><span>srand</span></span></a></div></div>
</td>
<td>   seeds pseudo-random number generator <br /> <span class="t-mark">(function)</span> <span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/numeric/random/dsc_srand&amp;action=edit">&#91;edit&#93;</a></span>
</td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="random/RAND_MAX.html" title="cpp/numeric/random/RAND MAX"> <span class="t-lines"><span>RAND_MAX</span></span></a></div></div>
</td>
<td>   maximum possible value generated by <span class="t-lc"><a href="random/rand.html" title="cpp/numeric/random/rand">std::rand</a></span> <br /> <span class="t-mark">(macro constant)</span> <span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/numeric/random/dsc_RAND_MAX&amp;action=edit">&#91;edit&#93;</a></span>
</td></tr>
</table>
<h3><span class="editsection">[<a href="http://en.cppreference.com/mwiki/index.php?title=cpp/numeric/random&amp;action=edit&amp;section=8" title="Edit section: Example">edit</a>]</span> <span class="mw-headline" id="Example">Example</span></h3>
<div class="t-example"><div class="t-example-live-link"><div class="coliru-btn coliru-btn-run-init">Run this code</div></div>
<div dir="ltr" class="mw-geshi" style="text-align: left;"><div class="cpp source-cpp"><pre class="de1"><span class="co2">#include &lt;iostream&gt;</span>
<span class="co2">#include &lt;iomanip&gt;</span>
<span class="co2">#include &lt;string&gt;</span>
<span class="co2">#include &lt;map&gt;</span>
<span class="co2">#include &lt;random&gt;</span>
<span class="co2">#include &lt;cmath&gt;</span>
&#160;
<span class="kw4">int</span> main<span class="br0">&#40;</span><span class="br0">&#41;</span>
<span class="br0">&#123;</span>
    <span class="co1">// Seed with a real random value, if available</span>
    <a href="random/random_device.html"><span class="kw1234">std::<span class="me2">random_device</span></span></a> rd<span class="sy4">;</span>
&#160;
    <span class="co1">// Choose a random mean between 1 and 6</span>
    std<span class="sy4">::</span><span class="me2">default_random_engine</span> e1<span class="br0">&#40;</span>rd<span class="br0">&#40;</span><span class="br0">&#41;</span><span class="br0">&#41;</span><span class="sy4">;</span>
    <a href="random/uniform_int_distribution.html"><span class="kw1249">std::<span class="me2">uniform_int_distribution</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span><span class="sy1">&gt;</span> uniform_dist<span class="br0">&#40;</span><span class="nu0">1</span>, <span class="nu0">6</span><span class="br0">&#41;</span><span class="sy4">;</span>
    <span class="kw4">int</span> mean <span class="sy1">=</span> uniform_dist<span class="br0">&#40;</span>e1<span class="br0">&#41;</span><span class="sy4">;</span>
    <a href="../io/cout.html"><span class="kw1480">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;Randomly-chosen mean: &quot;</span> <span class="sy1">&lt;&lt;</span> mean <span class="sy1">&lt;&lt;</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
&#160;
    <span class="co1">// Generate a normal distribution around that mean</span>
    <a href="random/mersenne_twister_engine.html"><span class="kw1237">std::<span class="me2">mt19937</span></span></a> e2<span class="br0">&#40;</span>rd<span class="br0">&#40;</span><span class="br0">&#41;</span><span class="br0">&#41;</span><span class="sy4">;</span>
    <a href="random/normal_distribution.html"><span class="kw1260">std::<span class="me2">normal_distribution</span></span></a><span class="sy1">&lt;&gt;</span> normal_dist<span class="br0">&#40;</span>mean, <span class="nu0">2</span><span class="br0">&#41;</span><span class="sy4">;</span>
&#160;
    <a href="../container/map.html"><span class="kw1100">std::<span class="me2">map</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span>, <span class="kw4">int</span><span class="sy1">&gt;</span> hist<span class="sy4">;</span>
    <span class="kw1">for</span> <span class="br0">&#40;</span><span class="kw4">int</span> n <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span> n <span class="sy1">&lt;</span> <span class="nu0">10000</span><span class="sy4">;</span> <span class="sy2">++</span>n<span class="br0">&#41;</span> <span class="br0">&#123;</span>
        <span class="sy2">++</span>hist<span class="br0">&#91;</span><a href="math/round.html"><span class="kw1164">std::<span class="me2">round</span></span></a><span class="br0">&#40;</span>normal_dist<span class="br0">&#40;</span>e2<span class="br0">&#41;</span><span class="br0">&#41;</span><span class="br0">&#93;</span><span class="sy4">;</span>
    <span class="br0">&#125;</span>
    <a href="../io/cout.html"><span class="kw1480">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;Normal distribution around &quot;</span> <span class="sy1">&lt;&lt;</span> mean <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;:<span class="es1">\n</span>&quot;</span><span class="sy4">;</span>
    <span class="kw1">for</span> <span class="br0">&#40;</span><span class="kw4">auto</span> p <span class="sy4">:</span> hist<span class="br0">&#41;</span> <span class="br0">&#123;</span>
        <a href="../io/cout.html"><span class="kw1480">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <a href="../io/manip/fixed.html"><span class="kw1506">std::<span class="me2">fixed</span></span></a> <span class="sy1">&lt;&lt;</span> <a href="../io/manip/setprecision.html"><span class="kw1518">std::<span class="me2">setprecision</span></span></a><span class="br0">&#40;</span><span class="nu0">1</span><span class="br0">&#41;</span> <span class="sy1">&lt;&lt;</span> <a href="../io/manip/setw.html"><span class="kw1519">std::<span class="me2">setw</span></span></a><span class="br0">&#40;</span><span class="nu0">2</span><span class="br0">&#41;</span>
                  <span class="sy1">&lt;&lt;</span> p.<span class="me1">first</span> <span class="sy1">&lt;&lt;</span> <span class="st0">' '</span> <span class="sy1">&lt;&lt;</span> <a href="../string/basic_string.html"><span class="kw1072">std::<span class="me2">string</span></span></a><span class="br0">&#40;</span>p.<span class="me1">second</span><span class="sy2">/</span><span class="nu0">200</span>, <span class="st0">'*'</span><span class="br0">&#41;</span> <span class="sy1">&lt;&lt;</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
    <span class="br0">&#125;</span>
<span class="br0">&#125;</span></pre></div></div>
<p>Possible output:
</p>
<div dir="ltr" class="mw-geshi" style="text-align: left;"><div class="text source-text"><pre class="de1">Randomly-chosen mean: 4
Normal distribution around 4:
-4 
-3 
-2 
-1 
 0 *
 1 ***
 2 ******
 3 ********
 4 *********
 5 ********
 6 ******
 7 ***
 8 *
 9 
10 
11 
12</pre></div></div> 
</div>
<h3><span class="editsection">[<a href="http://en.cppreference.com/mwiki/index.php?title=cpp/numeric/random&amp;action=edit&amp;section=9" title="Edit section: See also">edit</a>]</span> <span class="mw-headline" id="See_also">See also</span></h3>
<table class="t-dsc-begin">

<tr class="t-dsc">
<td colspan="2"> <div class="t-dsc-see"><span><a href="../../c/numeric/random.html" title="c/numeric/random">C documentation</a></span> for <span class="t-dsc-see-tt"><span>Pseudo-random number generation</span></span></div>
</td></tr>

</table>

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