d8bc09b616
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@104035 91177308-0d34-0410-b5e6-96231b3b80d8
105 lines
2.6 KiB
C++
105 lines
2.6 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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// <random>
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// template<class RealType = double>
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// class fisher_f_distribution
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// template<class _URNG> result_type operator()(_URNG& g);
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#include <random>
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#include <cassert>
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#include <vector>
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#include <algorithm>
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#include <cmath>
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double fac(double x)
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{
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double r = 1;
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for (; x > 1; --x)
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r *= x;
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return r;
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}
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double
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I(double x, unsigned a, unsigned b)
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{
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double r = 0;
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for (int j = a; j <= a+b-1; ++j)
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r += fac(a+b-1)/(fac(j) * fac(a + b - 1 - j)) * std::pow(x, j) *
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std::pow(1-x, a+b-1-j);
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return r;
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}
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double
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f(double x, double m, double n)
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{
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return I(m * x / (m*x + n), static_cast<unsigned>(m/2), static_cast<unsigned>(n/2));
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}
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int main()
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{
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// Purposefully only testing even integral values of m and n (for now)
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{
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typedef std::fisher_f_distribution<> D;
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typedef D::param_type P;
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typedef std::mt19937 G;
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G g;
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D d(2, 4);
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const int N = 100000;
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std::vector<D::result_type> u;
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for (int i = 0; i < N; ++i)
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{
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D::result_type v = d(g);
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assert(v >= 0);
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u.push_back(v);
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}
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std::sort(u.begin(), u.end());
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for (int i = 0; i < N; ++i)
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assert(std::abs(f(u[i], d.m(), d.n()) - double(i)/N) < .01);
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}
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{
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typedef std::fisher_f_distribution<> D;
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typedef D::param_type P;
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typedef std::mt19937 G;
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G g;
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D d(4, 2);
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const int N = 100000;
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std::vector<D::result_type> u;
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for (int i = 0; i < N; ++i)
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{
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D::result_type v = d(g);
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assert(v >= 0);
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u.push_back(v);
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}
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std::sort(u.begin(), u.end());
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for (int i = 0; i < N; ++i)
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assert(std::abs(f(u[i], d.m(), d.n()) - double(i)/N) < .01);
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}
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{
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typedef std::fisher_f_distribution<> D;
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typedef D::param_type P;
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typedef std::mt19937 G;
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G g;
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D d(18, 20);
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const int N = 100000;
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std::vector<D::result_type> u;
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for (int i = 0; i < N; ++i)
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{
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D::result_type v = d(g);
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assert(v >= 0);
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u.push_back(v);
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}
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std::sort(u.begin(), u.end());
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for (int i = 0; i < N; ++i)
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assert(std::abs(f(u[i], d.m(), d.n()) - double(i)/N) < .01);
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}
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}
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