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   static_assert(__libcpp_random_is_valid_realtype<_RealType>::value,
  30                 "RealType must be a supported floating-point type");
  31
  32 public:
  33   // types
  34   typedef _RealType result_type;
  35
  36   class _LIBCPP_TEMPLATE_VIS param_type {
  37     result_type __m_;
  38     result_type __n_;
  39
  40   public:
  41     typedef fisher_f_distribution distribution_type;
  42
  43     _LIBCPP_HIDE_FROM_ABI explicit param_type(result_type __m = 1, result_type __n = 1) : __m_(__m), __n_(__n) {}
  44
  45     _LIBCPP_HIDE_FROM_ABI result_type m() const { return __m_; }
  46     _LIBCPP_HIDE_FROM_ABI result_type n() const { return __n_; }
  47
  48     friend _LIBCPP_HIDE_FROM_ABI bool operator==(const param_type& __x, const param_type& __y) {
  49       return __x.__m_ == __y.__m_ && __x.__n_ == __y.__n_;
  50     }
  51     friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const param_type& __x, const param_type& __y) { return !(__x == __y); }
  52   };
  53
  54 private:
  55   param_type __p_;
  56
  57 public:
  58   // constructor and reset functions
  59 #ifndef _LIBCPP_CXX03_LANG
  60   _LIBCPP_HIDE_FROM_ABI fisher_f_distribution() : fisher_f_distribution(1) {}
  61   _LIBCPP_HIDE_FROM_ABI explicit fisher_f_distribution(result_type __m, result_type __n = 1)
  62       : __p_(param_type(__m, __n)) {}
  63 #else
  64   _LIBCPP_HIDE_FROM_ABI explicit fisher_f_distribution(result_type __m = 1, result_type __n = 1)
  65       : __p_(param_type(__m, __n)) {}
  66 #endif
  67   _LIBCPP_HIDE_FROM_ABI explicit fisher_f_distribution(const param_type& __p) : __p_(__p) {}
  68   _LIBCPP_HIDE_FROM_ABI void reset() {}
  69
  70   // generating functions
  71   template <class _URNG>
  72   _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) {
  73     return (*this)(__g, __p_);
  74   }
  75   template <class _URNG>
  76   _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);
  77
  78   // property functions
  79   _LIBCPP_HIDE_FROM_ABI result_type m() const { return __p_.m(); }
  80   _LIBCPP_HIDE_FROM_ABI result_type n() const { return __p_.n(); }
  81
  82   _LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; }
  83   _LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; }
  84
  85   _LIBCPP_HIDE_FROM_ABI result_type min() const { return 0; }
  86   _LIBCPP_HIDE_FROM_ABI result_type max() const { return numeric_limits<result_type>::infinity(); }
  87
  88   friend _LIBCPP_HIDE_FROM_ABI bool operator==(const fisher_f_distribution& __x, const fisher_f_distribution& __y) {
  89     return __x.__p_ == __y.__p_;
  90   }
  91   friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const fisher_f_distribution& __x, const fisher_f_distribution& __y) {
  92     return !(__x == __y);
  93   }
  94 };
  95
  96 template <class _RealType>
  97 template <class _URNG>
  98 _RealType fisher_f_distribution<_RealType>::operator()(_URNG& __g, const param_type& __p) {
  99   static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
 100   gamma_distribution<result_type> __gdm(__p.m() * result_type(.5));
 101   gamma_distribution<result_type> __gdn(__p.n() * result_type(.5));
 102   return __p.n() * __gdm(__g) / (__p.m() * __gdn(__g));
 103 }
 104
 105 template <class _CharT, class _Traits, class _RT>
 106 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
 107 operator<<(basic_ostream<_CharT, _Traits>& __os, const fisher_f_distribution<_RT>& __x) {
 108   __save_flags<_CharT, _Traits> __lx(__os);
 109   typedef basic_ostream<_CharT, _Traits> _OStream;
 110   __os.flags(_OStream::dec | _OStream::left | _OStream::fixed | _OStream::scientific);
 111   _CharT __sp = __os.widen(' ');
 112   __os.fill(__sp);
 113   __os << __x.m() << __sp << __x.n();
 114   return __os;
 115 }
 116
 117 template <class _CharT, class _Traits, class _RT>
 118 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
 119 operator>>(basic_istream<_CharT, _Traits>& __is, fisher_f_distribution<_RT>& __x) {
 120   typedef fisher_f_distribution<_RT> _Eng;
 121   typedef typename _Eng::result_type result_type;
 122   typedef typename _Eng::param_type param_type;
 123   __save_flags<_CharT, _Traits> __lx(__is);
 124   typedef basic_istream<_CharT, _Traits> _Istream;
 125   __is.flags(_Istream::dec | _Istream::skipws);
 126   result_type __m;
 127   result_type __n;
 128   __is >> __m >> __n;
 129   if (!__is.fail())
 130     __x.param(param_type(__m, __n));
 131   return __is;
 132 }
 133
 134 _LIBCPP_END_NAMESPACE_STD
 135
 136 _LIBCPP_POP_MACROS
 137
 138 #endif // _LIBCPP___RANDOM_FISHER_F_DISTRIBUTION_H