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);
17
18#include <random>
19
20#include <cassert>
21#include <cmath>
22#include <vector>
23#include <algorithm>
24
25#include "test_macros.h"
26
27double
28f(double x, double a, double b)
29{
30 return 1/3.1415926535897932 * std::atan(x: (x - a)/b) + .5;
31}
32
33int main(int, char**)
34{
35 {
36 typedef std::cauchy_distribution<> D;
37 typedef std::mt19937 G;
38 G g;
39 const double a = 10;
40 const double b = .5;
41 D d(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(x: d(g));
46 std::sort(first: u.begin(), last: u.end());
47 for (int i = 0; i < N; ++i)
48 assert(std::abs(f(u[i], a, b) - double(i) / N) < .0013);
49 }
50 {
51 typedef std::cauchy_distribution<> D;
52 typedef std::mt19937 G;
53 G g;
54 const double a = -1.5;
55 const double b = 1;
56 D d(a, b);
57 const int N = 1000000;
58 std::vector<D::result_type> u;
59 for (int i = 0; i < N; ++i)
60 u.push_back(x: d(g));
61 std::sort(first: u.begin(), last: u.end());
62 for (int i = 0; i < N; ++i)
63 assert(std::abs(f(u[i], a, b) - double(i) / N) < .0013);
64 }
65 {
66 typedef std::cauchy_distribution<> D;
67 typedef std::mt19937 G;
68 G g;
69 const double a = .5;
70 const double b = 2;
71 D d(a, b);
72 const int N = 1000000;
73 std::vector<D::result_type> u;
74 for (int i = 0; i < N; ++i)
75 u.push_back(x: d(g));
76 std::sort(first: u.begin(), last: u.end());
77 for (int i = 0; i < N; ++i)
78 assert(std::abs(f(u[i], a, b) - double(i) / N) < .0013);
79 }
80
81 return 0;
82}
83

source code of libcxx/test/std/numerics/rand/rand.dist/rand.dist.norm/rand.dist.norm.cauchy/eval.pass.cpp