libcxx/include/__random/cauchy_distribution.h

   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/uniform_real_distribution.h>
  14 #include <cmath>
  15 #include <iosfwd>
  16 #include <limits>
  17
  18 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  19 #pragma GCC system_header
  20 #endif
  21
  22 _LIBCPP_PUSH_MACROS
  23 #include <__undef_macros>
  24
  25 _LIBCPP_BEGIN_NAMESPACE_STD
  26
  27 template<class _RealType = double>
  28 class _LIBCPP_TEMPLATE_VIS cauchy_distribution
  29 {
  30 public:
  31     // types
  32     typedef _RealType result_type;
  33
  34     class _LIBCPP_TEMPLATE_VIS param_type
  35     {
  36         result_type __a_;
  37         result_type __b_;
  38     public:
  39         typedef cauchy_distribution distribution_type;
  40
  41         _LIBCPP_INLINE_VISIBILITY
  42         explicit param_type(result_type __a = 0, result_type __b = 1)
  43             : __a_(__a), __b_(__b) {}
  44
  45         _LIBCPP_INLINE_VISIBILITY
  46         result_type a() const {return __a_;}
  47         _LIBCPP_INLINE_VISIBILITY
  48         result_type b() const {return __b_;}
  49
  50         friend _LIBCPP_INLINE_VISIBILITY
  51             bool operator==(const param_type& __x, const param_type& __y)
  52             {return __x.__a_ == __y.__a_ && __x.__b_ == __y.__b_;}
  53         friend _LIBCPP_INLINE_VISIBILITY
  54             bool operator!=(const param_type& __x, const param_type& __y)
  55             {return !(__x == __y);}
  56     };
  57
  58 private:
  59     param_type __p_;
  60
  61 public:
  62     // constructor and reset functions
  63 #ifndef _LIBCPP_CXX03_LANG
  64     _LIBCPP_INLINE_VISIBILITY
  65     cauchy_distribution() : cauchy_distribution(0) {}
  66     _LIBCPP_INLINE_VISIBILITY
  67     explicit cauchy_distribution(result_type __a, result_type __b = 1)
  68         : __p_(param_type(__a, __b)) {}
  69 #else
  70     _LIBCPP_INLINE_VISIBILITY
  71     explicit cauchy_distribution(result_type __a = 0, result_type __b = 1)
  72         : __p_(param_type(__a, __b)) {}
  73 #endif
  74     _LIBCPP_INLINE_VISIBILITY
  75     explicit cauchy_distribution(const param_type& __p)
  76         : __p_(__p) {}
  77     _LIBCPP_INLINE_VISIBILITY
  78     void reset() {}
  79
  80     // generating functions
  81     template<class _URNG>
  82         _LIBCPP_INLINE_VISIBILITY
  83         result_type operator()(_URNG& __g)
  84         {return (*this)(__g, __p_);}
  85     template<class _URNG> _LIBCPP_INLINE_VISIBILITY result_type operator()(_URNG& __g, const param_type& __p);
  86
  87     // property functions
  88     _LIBCPP_INLINE_VISIBILITY
  89     result_type a() const {return __p_.a();}
  90     _LIBCPP_INLINE_VISIBILITY
  91     result_type b() const {return __p_.b();}
  92
  93     _LIBCPP_INLINE_VISIBILITY
  94     param_type param() const {return __p_;}
  95     _LIBCPP_INLINE_VISIBILITY
  96     void param(const param_type& __p) {__p_ = __p;}
  97
  98     _LIBCPP_INLINE_VISIBILITY
  99     result_type min() const {return -numeric_limits<result_type>::infinity();}
 100     _LIBCPP_INLINE_VISIBILITY
 101     result_type max() const {return numeric_limits<result_type>::infinity();}
 102
 103     friend _LIBCPP_INLINE_VISIBILITY
 104         bool operator==(const cauchy_distribution& __x,
 105                         const cauchy_distribution& __y)
 106         {return __x.__p_ == __y.__p_;}
 107     friend _LIBCPP_INLINE_VISIBILITY
 108         bool operator!=(const cauchy_distribution& __x,
 109                         const cauchy_distribution& __y)
 110         {return !(__x == __y);}
 111 };
 112
 113 template <class _RealType>
 114 template<class _URNG>
 115 inline
 116 _RealType
 117 cauchy_distribution<_RealType>::operator()(_URNG& __g, const param_type& __p)
 118 {
 119     uniform_real_distribution<result_type> __gen;
 120     // purposefully let tan arg get as close to pi/2 as it wants, tan will return a finite
 121     return __p.a() + __p.b() * _VSTD::tan(3.1415926535897932384626433832795 * __gen(__g));
 122 }
 123
 124 template <class _CharT, class _Traits, class _RT>
 125 basic_ostream<_CharT, _Traits>&
 126 operator<<(basic_ostream<_CharT, _Traits>& __os,
 127            const cauchy_distribution<_RT>& __x)
 128 {
 129     __save_flags<_CharT, _Traits> __lx(__os);
 130     typedef basic_ostream<_CharT, _Traits> _OStream;
 131     __os.flags(_OStream::dec | _OStream::left | _OStream::fixed |
 132                _OStream::scientific);
 133     _CharT __sp = __os.widen(' ');
 134     __os.fill(__sp);
 135     __os << __x.a() << __sp << __x.b();
 136     return __os;
 137 }
 138
 139 template <class _CharT, class _Traits, class _RT>
 140 basic_istream<_CharT, _Traits>&
 141 operator>>(basic_istream<_CharT, _Traits>& __is,
 142            cauchy_distribution<_RT>& __x)
 143 {
 144     typedef cauchy_distribution<_RT> _Eng;
 145     typedef typename _Eng::result_type result_type;
 146     typedef typename _Eng::param_type param_type;
 147     __save_flags<_CharT, _Traits> __lx(__is);
 148     typedef basic_istream<_CharT, _Traits> _Istream;
 149     __is.flags(_Istream::dec | _Istream::skipws);
 150     result_type __a;
 151     result_type __b;
 152     __is >> __a >> __b;
 153     if (!__is.fail())
 154         __x.param(param_type(__a, __b));
 155     return __is;
 156 }
 157
 158 _LIBCPP_END_NAMESPACE_STD
 159
 160 _LIBCPP_POP_MACROS
 161
 162 #endif // _LIBCPP___RANDOM_CAUCHY_DISTRIBUTION_H