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 <__random/is_valid.h>
  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 fisher_f_distribution
  29 {
  30 public:
  31     // types
  32     typedef _RealType result_type;
  33
  34     class _LIBCPP_TEMPLATE_VIS param_type
  35     {
  36         result_type __m_;
  37         result_type __n_;
  38     public:
  39         typedef fisher_f_distribution distribution_type;
  40
  41         _LIBCPP_INLINE_VISIBILITY
  42         explicit param_type(result_type __m = 1, result_type __n = 1)
  43             : __m_(__m), __n_(__n) {}
  44
  45         _LIBCPP_INLINE_VISIBILITY
  46         result_type m() const {return __m_;}
  47         _LIBCPP_INLINE_VISIBILITY
  48         result_type n() const {return __n_;}
  49
  50         friend _LIBCPP_INLINE_VISIBILITY
  51             bool operator==(const param_type& __x, const param_type& __y)
  52             {return __x.__m_ == __y.__m_ && __x.__n_ == __y.__n_;}
  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     fisher_f_distribution() : fisher_f_distribution(1) {}
  66     _LIBCPP_INLINE_VISIBILITY
  67     explicit fisher_f_distribution(result_type __m, result_type __n = 1)
  68         : __p_(param_type(__m, __n)) {}
  69 #else
  70     _LIBCPP_INLINE_VISIBILITY
  71     explicit fisher_f_distribution(result_type __m = 1, result_type __n = 1)
  72         : __p_(param_type(__m, __n)) {}
  73 #endif
  74     _LIBCPP_INLINE_VISIBILITY
  75     explicit fisher_f_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>
  86     _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);
  87
  88     // property functions
  89     _LIBCPP_INLINE_VISIBILITY
  90     result_type m() const {return __p_.m();}
  91     _LIBCPP_INLINE_VISIBILITY
  92     result_type n() const {return __p_.n();}
  93
  94     _LIBCPP_INLINE_VISIBILITY
  95     param_type param() const {return __p_;}
  96     _LIBCPP_INLINE_VISIBILITY
  97     void param(const param_type& __p) {__p_ = __p;}
  98
  99     _LIBCPP_INLINE_VISIBILITY
 100     result_type min() const {return 0;}
 101     _LIBCPP_INLINE_VISIBILITY
 102     result_type max() const {return numeric_limits<result_type>::infinity();}
 103
 104     friend _LIBCPP_INLINE_VISIBILITY
 105         bool operator==(const fisher_f_distribution& __x,
 106                         const fisher_f_distribution& __y)
 107         {return __x.__p_ == __y.__p_;}
 108     friend _LIBCPP_INLINE_VISIBILITY
 109         bool operator!=(const fisher_f_distribution& __x,
 110                         const fisher_f_distribution& __y)
 111         {return !(__x == __y);}
 112 };
 113
 114 template <class _RealType>
 115 template<class _URNG>
 116 _RealType
 117 fisher_f_distribution<_RealType>::operator()(_URNG& __g, const param_type& __p)
 118 {
 119     static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
 120     gamma_distribution<result_type> __gdm(__p.m() * result_type(.5));
 121     gamma_distribution<result_type> __gdn(__p.n() * result_type(.5));
 122     return __p.n() * __gdm(__g) / (__p.m() * __gdn(__g));
 123 }
 124
 125 template <class _CharT, class _Traits, class _RT>
 126 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
 127 operator<<(basic_ostream<_CharT, _Traits>& __os,
 128            const fisher_f_distribution<_RT>& __x)
 129 {
 130     __save_flags<_CharT, _Traits> __lx(__os);
 131     typedef basic_ostream<_CharT, _Traits> _OStream;
 132     __os.flags(_OStream::dec | _OStream::left | _OStream::fixed |
 133                _OStream::scientific);
 134     _CharT __sp = __os.widen(' ');
 135     __os.fill(__sp);
 136     __os << __x.m() << __sp << __x.n();
 137     return __os;
 138 }
 139
 140 template <class _CharT, class _Traits, class _RT>
 141 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
 142 operator>>(basic_istream<_CharT, _Traits>& __is,
 143            fisher_f_distribution<_RT>& __x)
 144 {
 145     typedef fisher_f_distribution<_RT> _Eng;
 146     typedef typename _Eng::result_type result_type;
 147     typedef typename _Eng::param_type param_type;
 148     __save_flags<_CharT, _Traits> __lx(__is);
 149     typedef basic_istream<_CharT, _Traits> _Istream;
 150     __is.flags(_Istream::dec | _Istream::skipws);
 151     result_type __m;
 152     result_type __n;
 153     __is >> __m >> __n;
 154     if (!__is.fail())
 155         __x.param(param_type(__m, __n));
 156     return __is;
 157 }
 158
 159 _LIBCPP_END_NAMESPACE_STD
 160
 161 _LIBCPP_POP_MACROS
 162
 163 #endif // _LIBCPP___RANDOM_FISHER_F_DISTRIBUTION_H