libcxx/include/__cxx03/__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 <__cxx03/__config>
  13 #include <__cxx03/__random/is_valid.h>
  14 #include <__cxx03/__random/uniform_real_distribution.h>
  15 #include <__cxx03/cmath>
  16 #include <__cxx03/iosfwd>
  17 #include <__cxx03/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 <__cxx03/__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