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#ifndef _LIBCPP___RANDOM_CAUCHY_DISTRIBUTION_H
10#define _LIBCPP___RANDOM_CAUCHY_DISTRIBUTION_H
11
12#include <__config>
13#include <__random/is_valid.h>
14#include <__random/uniform_real_distribution.h>
15#include <cmath>
16#include <iosfwd>
17#include <limits>
18
19#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
20# pragma GCC system_header
21#endif
22
23_LIBCPP_PUSH_MACROS
24#include <__undef_macros>
25
26_LIBCPP_BEGIN_NAMESPACE_STD
27
28template <class _RealType = double>
29class cauchy_distribution {
30 static_assert(__libcpp_random_is_valid_realtype<_RealType>::value,
31 "RealType must be a supported floating-point type");
32
33public:
34 // types
35 typedef _RealType result_type;
36
37 class param_type {
38 result_type __a_;
39 result_type __b_;
40
41 public:
42 typedef cauchy_distribution distribution_type;
43
44 _LIBCPP_HIDE_FROM_ABI explicit param_type(result_type __a = 0, result_type __b = 1) : __a_(__a), __b_(__b) {}
45
46 _LIBCPP_HIDE_FROM_ABI result_type a() const { return __a_; }
47 _LIBCPP_HIDE_FROM_ABI result_type b() const { return __b_; }
48
49 friend _LIBCPP_HIDE_FROM_ABI bool operator==(const param_type& __x, const param_type& __y) {
50 return __x.__a_ == __y.__a_ && __x.__b_ == __y.__b_;
51 }
52 friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const param_type& __x, const param_type& __y) { return !(__x == __y); }
53 };
54
55private:
56 param_type __p_;
57
58public:
59 // constructor and reset functions
60#ifndef _LIBCPP_CXX03_LANG
61 _LIBCPP_HIDE_FROM_ABI cauchy_distribution() : cauchy_distribution(0) {}
62 _LIBCPP_HIDE_FROM_ABI explicit cauchy_distribution(result_type __a, result_type __b = 1)
63 : __p_(param_type(__a, __b)) {}
64#else
65 _LIBCPP_HIDE_FROM_ABI explicit cauchy_distribution(result_type __a = 0, result_type __b = 1)
66 : __p_(param_type(__a, __b)) {}
67#endif
68 _LIBCPP_HIDE_FROM_ABI explicit cauchy_distribution(const param_type& __p) : __p_(__p) {}
69 _LIBCPP_HIDE_FROM_ABI void reset() {}
70
71 // generating functions
72 template <class _URNG>
73 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) {
74 return (*this)(__g, __p_);
75 }
76 template <class _URNG>
77 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);
78
79 // property functions
80 _LIBCPP_HIDE_FROM_ABI result_type a() const { return __p_.a(); }
81 _LIBCPP_HIDE_FROM_ABI result_type b() const { return __p_.b(); }
82
83 _LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; }
84 _LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; }
85
86 _LIBCPP_HIDE_FROM_ABI result_type min() const { return -numeric_limits<result_type>::infinity(); }
87 _LIBCPP_HIDE_FROM_ABI result_type max() const { return numeric_limits<result_type>::infinity(); }
88
89 friend _LIBCPP_HIDE_FROM_ABI bool operator==(const cauchy_distribution& __x, const cauchy_distribution& __y) {
90 return __x.__p_ == __y.__p_;
91 }
92 friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const cauchy_distribution& __x, const cauchy_distribution& __y) {
93 return !(__x == __y);
94 }
95};
96
97template <class _RealType>
98template <class _URNG>
99inline _RealType cauchy_distribution<_RealType>::operator()(_URNG& __g, const param_type& __p) {
100 static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
101 uniform_real_distribution<result_type> __gen;
102 // purposefully let tan arg get as close to pi/2 as it wants, tan will return a finite
103 return __p.a() + __p.b() * std::tan(3.1415926535897932384626433832795 * __gen(__g));
104}
105
106template <class _CharT, class _Traits, class _RT>
107_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
108operator<<(basic_ostream<_CharT, _Traits>& __os, const cauchy_distribution<_RT>& __x) {
109 __save_flags<_CharT, _Traits> __lx(__os);
110 typedef basic_ostream<_CharT, _Traits> _OStream;
111 __os.flags(_OStream::dec | _OStream::left | _OStream::fixed | _OStream::scientific);
112 _CharT __sp = __os.widen(' ');
113 __os.fill(__sp);
114 __os << __x.a() << __sp << __x.b();
115 return __os;
116}
117
118template <class _CharT, class _Traits, class _RT>
119_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
120operator>>(basic_istream<_CharT, _Traits>& __is, cauchy_distribution<_RT>& __x) {
121 typedef cauchy_distribution<_RT> _Eng;
122 typedef typename _Eng::result_type result_type;
123 typedef typename _Eng::param_type param_type;
124 __save_flags<_CharT, _Traits> __lx(__is);
125 typedef basic_istream<_CharT, _Traits> _Istream;
126 __is.flags(_Istream::dec | _Istream::skipws);
127 result_type __a;
128 result_type __b;
129 __is >> __a >> __b;
130 if (!__is.fail())
131 __x.param(param_type(__a, __b));
132 return __is;
133}
134
135_LIBCPP_END_NAMESPACE_STD
136
137_LIBCPP_POP_MACROS
138
139#endif // _LIBCPP___RANDOM_CAUCHY_DISTRIBUTION_H
140