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 28 template <class _RealType = double> 29 class _LIBCPP_TEMPLATE_VIS cauchy_distribution { 30 static_assert(__libcpp_random_is_valid_realtype<_RealType>::value, 31 "RealType must be a supported floating-point type"); 32 33 public: 34 // types 35 typedef _RealType result_type; 36 37 class _LIBCPP_TEMPLATE_VIS 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 55 private: 56 param_type __p_; 57 58 public: 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 97 template <class _RealType> 98 template <class _URNG> 99 inline _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 } 105 106 template <class _CharT, class _Traits, class _RT> 107 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>& 108 operator<<(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 } 117 118 template <class _CharT, class _Traits, class _RT> 119 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>& 120 operator>>(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