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
20 #include <cassert>
21 #include <cmath>
22 #include <vector>
23 #include <algorithm>
24
25 #include "test_macros.h"
26
27 double
f(double x,double a,double b)28 f(double x, double a, double b)
29 {
30 return 1/3.1415926535897932 * std::atan((x - a)/b) + .5;
31 }
32
main(int,char **)33 int main(int, char**)
34 {
35 {
36 typedef std::cauchy_distribution<> D;
37 typedef D::param_type P;
38 typedef std::mt19937 G;
39 G g;
40 const double a = 10;
41 const double b = .5;
42 D d;
43 P p(a, b);
44 const int N = 1000000;
45 std::vector<D::result_type> u;
46 for (int i = 0; i < N; ++i)
47 u.push_back(d(g, p));
48 std::sort(u.begin(), u.end());
49 for (int i = 0; i < N; ++i)
50 assert(std::abs(f(u[i], a, b) - double(i)/N) < .001);
51 }
52 {
53 typedef std::cauchy_distribution<> D;
54 typedef D::param_type P;
55 typedef std::mt19937 G;
56 G g;
57 const double a = -1.5;
58 const double b = 1;
59 D d;
60 P p(a, b);
61 const int N = 1000000;
62 std::vector<D::result_type> u;
63 for (int i = 0; i < N; ++i)
64 u.push_back(d(g, p));
65 std::sort(u.begin(), u.end());
66 for (int i = 0; i < N; ++i)
67 assert(std::abs(f(u[i], a, b) - double(i)/N) < .001);
68 }
69 {
70 typedef std::cauchy_distribution<> D;
71 typedef D::param_type P;
72 typedef std::mt19937 G;
73 G g;
74 const double a = .5;
75 const double b = 2;
76 D d;
77 P p(a, b);
78 const int N = 1000000;
79 std::vector<D::result_type> u;
80 for (int i = 0; i < N; ++i)
81 u.push_back(d(g, p));
82 std::sort(u.begin(), u.end());
83 for (int i = 0; i < N; ++i)
84 assert(std::abs(f(u[i], a, b) - double(i)/N) < .001);
85 }
86
87 return 0;
88 }
89