1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // REQUIRES: long_tests
10
11 // <random>
12
13 // template<class RealType = double>
14 // class cauchy_distribution
15
16 // template<class _URNG> result_type operator()(_URNG& g, const param_type& parm);
17
18 #include <random>
19 #include <cassert>
20 #include <vector>
21 #include <algorithm>
22
23 #include "test_macros.h"
24
25 double
f(double x,double a,double b)26 f(double x, double a, double b)
27 {
28 return 1/3.1415926535897932 * std::atan((x - a)/b) + .5;
29 }
30
main(int,char **)31 int main(int, char**)
32 {
33 {
34 typedef std::cauchy_distribution<> D;
35 typedef D::param_type P;
36 typedef std::mt19937 G;
37 G g;
38 const double a = 10;
39 const double b = .5;
40 D d;
41 P p(a, b);
42 const int N = 1000000;
43 std::vector<D::result_type> u;
44 for (int i = 0; i < N; ++i)
45 u.push_back(d(g, p));
46 std::sort(u.begin(), u.end());
47 for (int i = 0; i < N; ++i)
48 assert(std::abs(f(u[i], a, b) - double(i)/N) < .001);
49 }
50 {
51 typedef std::cauchy_distribution<> D;
52 typedef D::param_type P;
53 typedef std::mt19937 G;
54 G g;
55 const double a = -1.5;
56 const double b = 1;
57 D d;
58 P p(a, b);
59 const int N = 1000000;
60 std::vector<D::result_type> u;
61 for (int i = 0; i < N; ++i)
62 u.push_back(d(g, p));
63 std::sort(u.begin(), u.end());
64 for (int i = 0; i < N; ++i)
65 assert(std::abs(f(u[i], a, b) - double(i)/N) < .001);
66 }
67 {
68 typedef std::cauchy_distribution<> D;
69 typedef D::param_type P;
70 typedef std::mt19937 G;
71 G g;
72 const double a = .5;
73 const double b = 2;
74 D d;
75 P p(a, b);
76 const int N = 1000000;
77 std::vector<D::result_type> u;
78 for (int i = 0; i < N; ++i)
79 u.push_back(d(g, p));
80 std::sort(u.begin(), u.end());
81 for (int i = 0; i < N; ++i)
82 assert(std::abs(f(u[i], a, b) - double(i)/N) < .001);
83 }
84
85 return 0;
86 }
87