Howard Hinnant 551d8e4ddb [rand.dist.samp.discrete]
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@104103 91177308-0d34-0410-b5e6-96231b3b80d8
2010-05-19 01:53:57 +00:00

44 lines
1.2 KiB
C++

//===----------------------------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
// <random>
// template<class IntType = int>
// class discrete_distribution
// template<class _URNG> result_type operator()(_URNG& g, const param_type& parm);
#include <random>
#include <vector>
#include <cassert>
int main()
{
{
typedef std::discrete_distribution<> D;
typedef D::param_type P;
typedef std::minstd_rand G;
G g;
D d;
double p0[] = {.3, .1, .6};
P p(p0, p0+3);
const int N = 10000000;
std::vector<D::result_type> u(3);
for (int i = 0; i < N; ++i)
{
D::result_type v = d(g, p);
assert(0 <= v && v <= 2);
u[v]++;
}
std::vector<double> prob = p.probabilities();
for (int i = 0; i <= 2; ++i)
assert(std::abs((double)u[i]/N - prob[i]) / prob[i] < 0.001);
}
}