libcxx/include/__random/fisher_f_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_FISHER_F_DISTRIBUTION_H
  10 #define _LIBCPP___RANDOM_FISHER_F_DISTRIBUTION_H
  11
  12 #include <__config>
  13 #include <__random/gamma_distribution.h>
  14 #include <iosfwd>
  15 #include <limits>
  16
  17 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  18 #pragma GCC system_header
  19 #endif
  20
  21 _LIBCPP_PUSH_MACROS
  22 #include <__undef_macros>
  23
  24 _LIBCPP_BEGIN_NAMESPACE_STD
  25
  26 template<class _RealType = double>
  27 class _LIBCPP_TEMPLATE_VIS fisher_f_distribution
  28 {
  29 public:
  30     // types
  31     typedef _RealType result_type;
  32
  33     class _LIBCPP_TEMPLATE_VIS param_type
  34     {
  35         result_type __m_;
  36         result_type __n_;
  37     public:
  38         typedef fisher_f_distribution distribution_type;
  39
  40         _LIBCPP_INLINE_VISIBILITY
  41         explicit param_type(result_type __m = 1, result_type __n = 1)
  42             : __m_(__m), __n_(__n) {}
  43
  44         _LIBCPP_INLINE_VISIBILITY
  45         result_type m() const {return __m_;}
  46         _LIBCPP_INLINE_VISIBILITY
  47         result_type n() const {return __n_;}
  48
  49         friend _LIBCPP_INLINE_VISIBILITY
  50             bool operator==(const param_type& __x, const param_type& __y)
  51             {return __x.__m_ == __y.__m_ && __x.__n_ == __y.__n_;}
  52         friend _LIBCPP_INLINE_VISIBILITY
  53             bool operator!=(const param_type& __x, const param_type& __y)
  54             {return !(__x == __y);}
  55     };
  56
  57 private:
  58     param_type __p_;
  59
  60 public:
  61     // constructor and reset functions
  62 #ifndef _LIBCPP_CXX03_LANG
  63     _LIBCPP_INLINE_VISIBILITY
  64     fisher_f_distribution() : fisher_f_distribution(1) {}
  65     _LIBCPP_INLINE_VISIBILITY
  66     explicit fisher_f_distribution(result_type __m, result_type __n = 1)
  67         : __p_(param_type(__m, __n)) {}
  68 #else
  69     _LIBCPP_INLINE_VISIBILITY
  70     explicit fisher_f_distribution(result_type __m = 1, result_type __n = 1)
  71         : __p_(param_type(__m, __n)) {}
  72 #endif
  73     _LIBCPP_INLINE_VISIBILITY
  74     explicit fisher_f_distribution(const param_type& __p)
  75         : __p_(__p) {}
  76     _LIBCPP_INLINE_VISIBILITY
  77     void reset() {}
  78
  79     // generating functions
  80     template<class _URNG>
  81         _LIBCPP_INLINE_VISIBILITY
  82         result_type operator()(_URNG& __g)
  83         {return (*this)(__g, __p_);}
  84     template<class _URNG> result_type operator()(_URNG& __g, const param_type& __p);
  85
  86     // property functions
  87     _LIBCPP_INLINE_VISIBILITY
  88     result_type m() const {return __p_.m();}
  89     _LIBCPP_INLINE_VISIBILITY
  90     result_type n() const {return __p_.n();}
  91
  92     _LIBCPP_INLINE_VISIBILITY
  93     param_type param() const {return __p_;}
  94     _LIBCPP_INLINE_VISIBILITY
  95     void param(const param_type& __p) {__p_ = __p;}
  96
  97     _LIBCPP_INLINE_VISIBILITY
  98     result_type min() const {return 0;}
  99     _LIBCPP_INLINE_VISIBILITY
 100     result_type max() const {return numeric_limits<result_type>::infinity();}
 101
 102     friend _LIBCPP_INLINE_VISIBILITY
 103         bool operator==(const fisher_f_distribution& __x,
 104                         const fisher_f_distribution& __y)
 105         {return __x.__p_ == __y.__p_;}
 106     friend _LIBCPP_INLINE_VISIBILITY
 107         bool operator!=(const fisher_f_distribution& __x,
 108                         const fisher_f_distribution& __y)
 109         {return !(__x == __y);}
 110 };
 111
 112 template <class _RealType>
 113 template<class _URNG>
 114 _RealType
 115 fisher_f_distribution<_RealType>::operator()(_URNG& __g, const param_type& __p)
 116 {
 117     gamma_distribution<result_type> __gdm(__p.m() * result_type(.5));
 118     gamma_distribution<result_type> __gdn(__p.n() * result_type(.5));
 119     return __p.n() * __gdm(__g) / (__p.m() * __gdn(__g));
 120 }
 121
 122 template <class _CharT, class _Traits, class _RT>
 123 basic_ostream<_CharT, _Traits>&
 124 operator<<(basic_ostream<_CharT, _Traits>& __os,
 125            const fisher_f_distribution<_RT>& __x)
 126 {
 127     __save_flags<_CharT, _Traits> __lx(__os);
 128     typedef basic_ostream<_CharT, _Traits> _OStream;
 129     __os.flags(_OStream::dec | _OStream::left | _OStream::fixed |
 130                _OStream::scientific);
 131     _CharT __sp = __os.widen(' ');
 132     __os.fill(__sp);
 133     __os << __x.m() << __sp << __x.n();
 134     return __os;
 135 }
 136
 137 template <class _CharT, class _Traits, class _RT>
 138 basic_istream<_CharT, _Traits>&
 139 operator>>(basic_istream<_CharT, _Traits>& __is,
 140            fisher_f_distribution<_RT>& __x)
 141 {
 142     typedef fisher_f_distribution<_RT> _Eng;
 143     typedef typename _Eng::result_type result_type;
 144     typedef typename _Eng::param_type param_type;
 145     __save_flags<_CharT, _Traits> __lx(__is);
 146     typedef basic_istream<_CharT, _Traits> _Istream;
 147     __is.flags(_Istream::dec | _Istream::skipws);
 148     result_type __m;
 149     result_type __n;
 150     __is >> __m >> __n;
 151     if (!__is.fail())
 152         __x.param(param_type(__m, __n));
 153     return __is;
 154 }
 155
 156 _LIBCPP_END_NAMESPACE_STD
 157
 158 _LIBCPP_POP_MACROS
 159
 160 #endif // _LIBCPP___RANDOM_FISHER_F_DISTRIBUTION_H