1//===----------------------------------------------------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is dual licensed under the MIT and the University of Illinois Open
6// Source Licenses. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10// <random>
11
12// template<class RealType = double>
13// class cauchy_distribution
14
15// template<class _URNG> result_type operator()(_URNG& g);
16
17#include <random>
18#include <cassert>
19#include <vector>
20#include <algorithm>
21
22double
23f(double x, double a, double b)
24{
25    return 1/3.1415926535897932 * std::atan((x - a)/b) + .5;
26}
27
28int main()
29{
30    {
31        typedef std::cauchy_distribution<> D;
32        typedef D::param_type P;
33        typedef std::mt19937 G;
34        G g;
35        const double a = 10;
36        const double b = .5;
37        D d(a, b);
38        const int N = 1000000;
39        std::vector<D::result_type> u;
40        for (int i = 0; i < N; ++i)
41            u.push_back(d(g));
42        std::sort(u.begin(), u.end());
43        for (int i = 0; i < N; ++i)
44            assert(std::abs(f(u[i], a, b) - double(i)/N) < .001);
45    }
46    {
47        typedef std::cauchy_distribution<> D;
48        typedef D::param_type P;
49        typedef std::mt19937 G;
50        G g;
51        const double a = -1.5;
52        const double b = 1;
53        D d(a, b);
54        const int N = 1000000;
55        std::vector<D::result_type> u;
56        for (int i = 0; i < N; ++i)
57            u.push_back(d(g));
58        std::sort(u.begin(), u.end());
59        for (int i = 0; i < N; ++i)
60            assert(std::abs(f(u[i], a, b) - double(i)/N) < .001);
61    }
62    {
63        typedef std::cauchy_distribution<> D;
64        typedef D::param_type P;
65        typedef std::mt19937 G;
66        G g;
67        const double a = .5;
68        const double b = 2;
69        D d(a, b);
70        const int N = 1000000;
71        std::vector<D::result_type> u;
72        for (int i = 0; i < N; ++i)
73            u.push_back(d(g));
74        std::sort(u.begin(), u.end());
75        for (int i = 0; i < N; ++i)
76            assert(std::abs(f(u[i], a, b) - double(i)/N) < .001);
77    }
78}
79