xref: /freebsd-src/contrib/llvm-project/libcxx/include/__random/negative_binomial_distribution.h (revision 0fca6ea1d4eea4c934cfff25ac9ee8ad6fe95583)
14824e7fdSDimitry Andric //===----------------------------------------------------------------------===//
24824e7fdSDimitry Andric //
34824e7fdSDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
44824e7fdSDimitry Andric // See https://llvm.org/LICENSE.txt for license information.
54824e7fdSDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
64824e7fdSDimitry Andric //
74824e7fdSDimitry Andric //===----------------------------------------------------------------------===//
84824e7fdSDimitry Andric 
94824e7fdSDimitry Andric #ifndef _LIBCPP___RANDOM_NEGATIVE_BINOMIAL_DISTRIBUTION_H
104824e7fdSDimitry Andric #define _LIBCPP___RANDOM_NEGATIVE_BINOMIAL_DISTRIBUTION_H
114824e7fdSDimitry Andric 
12*0fca6ea1SDimitry Andric #include <__assert>
134824e7fdSDimitry Andric #include <__config>
144824e7fdSDimitry Andric #include <__random/bernoulli_distribution.h>
154824e7fdSDimitry Andric #include <__random/gamma_distribution.h>
1681ad6265SDimitry Andric #include <__random/is_valid.h>
174824e7fdSDimitry Andric #include <__random/poisson_distribution.h>
184824e7fdSDimitry Andric #include <iosfwd>
194824e7fdSDimitry Andric #include <limits>
204824e7fdSDimitry Andric 
214824e7fdSDimitry Andric #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
224824e7fdSDimitry Andric #  pragma GCC system_header
234824e7fdSDimitry Andric #endif
244824e7fdSDimitry Andric 
254824e7fdSDimitry Andric _LIBCPP_PUSH_MACROS
264824e7fdSDimitry Andric #include <__undef_macros>
274824e7fdSDimitry Andric 
284824e7fdSDimitry Andric _LIBCPP_BEGIN_NAMESPACE_STD
294824e7fdSDimitry Andric 
304824e7fdSDimitry Andric template <class _IntType = int>
31cb14a3feSDimitry Andric class _LIBCPP_TEMPLATE_VIS negative_binomial_distribution {
32fcaf7f86SDimitry Andric   static_assert(__libcpp_random_is_valid_inttype<_IntType>::value, "IntType must be a supported integer type");
33cb14a3feSDimitry Andric 
344824e7fdSDimitry Andric public:
354824e7fdSDimitry Andric   // types
364824e7fdSDimitry Andric   typedef _IntType result_type;
374824e7fdSDimitry Andric 
38cb14a3feSDimitry Andric   class _LIBCPP_TEMPLATE_VIS param_type {
394824e7fdSDimitry Andric     result_type __k_;
404824e7fdSDimitry Andric     double __p_;
41cb14a3feSDimitry Andric 
424824e7fdSDimitry Andric   public:
434824e7fdSDimitry Andric     typedef negative_binomial_distribution distribution_type;
444824e7fdSDimitry Andric 
45cb14a3feSDimitry Andric     _LIBCPP_HIDE_FROM_ABI explicit param_type(result_type __k = 1, double __p = 0.5) : __k_(__k), __p_(__p) {}
464824e7fdSDimitry Andric 
47cb14a3feSDimitry Andric     _LIBCPP_HIDE_FROM_ABI result_type k() const { return __k_; }
48cb14a3feSDimitry Andric     _LIBCPP_HIDE_FROM_ABI double p() const { return __p_; }
494824e7fdSDimitry Andric 
50cb14a3feSDimitry Andric     friend _LIBCPP_HIDE_FROM_ABI bool operator==(const param_type& __x, const param_type& __y) {
51cb14a3feSDimitry Andric       return __x.__k_ == __y.__k_ && __x.__p_ == __y.__p_;
52cb14a3feSDimitry Andric     }
53cb14a3feSDimitry Andric     friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const param_type& __x, const param_type& __y) { return !(__x == __y); }
544824e7fdSDimitry Andric   };
554824e7fdSDimitry Andric 
564824e7fdSDimitry Andric private:
574824e7fdSDimitry Andric   param_type __p_;
584824e7fdSDimitry Andric 
594824e7fdSDimitry Andric public:
604824e7fdSDimitry Andric   // constructor and reset functions
614824e7fdSDimitry Andric #ifndef _LIBCPP_CXX03_LANG
62cb14a3feSDimitry Andric   _LIBCPP_HIDE_FROM_ABI negative_binomial_distribution() : negative_binomial_distribution(1) {}
63cb14a3feSDimitry Andric   _LIBCPP_HIDE_FROM_ABI explicit negative_binomial_distribution(result_type __k, double __p = 0.5) : __p_(__k, __p) {}
644824e7fdSDimitry Andric #else
65cb14a3feSDimitry Andric   _LIBCPP_HIDE_FROM_ABI explicit negative_binomial_distribution(result_type __k = 1, double __p = 0.5)
664824e7fdSDimitry Andric       : __p_(__k, __p) {}
674824e7fdSDimitry Andric #endif
68cb14a3feSDimitry Andric   _LIBCPP_HIDE_FROM_ABI explicit negative_binomial_distribution(const param_type& __p) : __p_(__p) {}
69cb14a3feSDimitry Andric   _LIBCPP_HIDE_FROM_ABI void reset() {}
704824e7fdSDimitry Andric 
714824e7fdSDimitry Andric   // generating functions
724824e7fdSDimitry Andric   template <class _URNG>
73cb14a3feSDimitry Andric   _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) {
74cb14a3feSDimitry Andric     return (*this)(__g, __p_);
75cb14a3feSDimitry Andric   }
7606c3fb27SDimitry Andric   template <class _URNG>
7706c3fb27SDimitry Andric   _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);
784824e7fdSDimitry Andric 
794824e7fdSDimitry Andric   // property functions
80cb14a3feSDimitry Andric   _LIBCPP_HIDE_FROM_ABI result_type k() const { return __p_.k(); }
81cb14a3feSDimitry Andric   _LIBCPP_HIDE_FROM_ABI double p() const { return __p_.p(); }
824824e7fdSDimitry Andric 
83cb14a3feSDimitry Andric   _LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; }
84cb14a3feSDimitry Andric   _LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; }
854824e7fdSDimitry Andric 
86cb14a3feSDimitry Andric   _LIBCPP_HIDE_FROM_ABI result_type min() const { return 0; }
87cb14a3feSDimitry Andric   _LIBCPP_HIDE_FROM_ABI result_type max() const { return numeric_limits<result_type>::max(); }
884824e7fdSDimitry Andric 
89cb14a3feSDimitry Andric   friend _LIBCPP_HIDE_FROM_ABI bool
90cb14a3feSDimitry Andric   operator==(const negative_binomial_distribution& __x, const negative_binomial_distribution& __y) {
91cb14a3feSDimitry Andric     return __x.__p_ == __y.__p_;
92cb14a3feSDimitry Andric   }
93cb14a3feSDimitry Andric   friend _LIBCPP_HIDE_FROM_ABI bool
94cb14a3feSDimitry Andric   operator!=(const negative_binomial_distribution& __x, const negative_binomial_distribution& __y) {
95cb14a3feSDimitry Andric     return !(__x == __y);
96cb14a3feSDimitry Andric   }
974824e7fdSDimitry Andric };
984824e7fdSDimitry Andric 
994824e7fdSDimitry Andric template <class _IntType>
1004824e7fdSDimitry Andric template <class _URNG>
101cb14a3feSDimitry Andric _IntType negative_binomial_distribution<_IntType>::operator()(_URNG& __urng, const param_type& __pr) {
10281ad6265SDimitry Andric   static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
1034824e7fdSDimitry Andric   result_type __k = __pr.k();
1044824e7fdSDimitry Andric   double __p      = __pr.p();
105fcaf7f86SDimitry Andric   // When the number of bits in _IntType is small, we are too likely to
106fcaf7f86SDimitry Andric   // overflow __f below to use this technique.
107cb14a3feSDimitry Andric   if (__k <= 21 * __p && sizeof(_IntType) > 1) {
1084824e7fdSDimitry Andric     bernoulli_distribution __gen(__p);
1094824e7fdSDimitry Andric     result_type __f = 0;
1104824e7fdSDimitry Andric     result_type __s = 0;
111cb14a3feSDimitry Andric     while (__s < __k) {
1124824e7fdSDimitry Andric       if (__gen(__urng))
1134824e7fdSDimitry Andric         ++__s;
1144824e7fdSDimitry Andric       else
1154824e7fdSDimitry Andric         ++__f;
1164824e7fdSDimitry Andric     }
1171db9f3b2SDimitry Andric     _LIBCPP_ASSERT_INTERNAL(__f >= 0,
11806c3fb27SDimitry Andric                             "std::negative_binomial_distribution should never produce negative values. "
119fcaf7f86SDimitry Andric                             "This is almost certainly a signed integer overflow issue on __f.");
1204824e7fdSDimitry Andric     return __f;
1214824e7fdSDimitry Andric   }
122cb14a3feSDimitry Andric   return poisson_distribution<result_type>(gamma_distribution<double>(__k, (1 - __p) / __p)(__urng))(__urng);
1234824e7fdSDimitry Andric }
1244824e7fdSDimitry Andric 
1254824e7fdSDimitry Andric template <class _CharT, class _Traits, class _IntType>
126bdd1243dSDimitry Andric _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
127cb14a3feSDimitry Andric operator<<(basic_ostream<_CharT, _Traits>& __os, const negative_binomial_distribution<_IntType>& __x) {
1284824e7fdSDimitry Andric   __save_flags<_CharT, _Traits> __lx(__os);
1294824e7fdSDimitry Andric   typedef basic_ostream<_CharT, _Traits> _OStream;
130cb14a3feSDimitry Andric   __os.flags(_OStream::dec | _OStream::left | _OStream::fixed | _OStream::scientific);
1314824e7fdSDimitry Andric   _CharT __sp = __os.widen(' ');
1324824e7fdSDimitry Andric   __os.fill(__sp);
1334824e7fdSDimitry Andric   return __os << __x.k() << __sp << __x.p();
1344824e7fdSDimitry Andric }
1354824e7fdSDimitry Andric 
1364824e7fdSDimitry Andric template <class _CharT, class _Traits, class _IntType>
137bdd1243dSDimitry Andric _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
138cb14a3feSDimitry Andric operator>>(basic_istream<_CharT, _Traits>& __is, negative_binomial_distribution<_IntType>& __x) {
1394824e7fdSDimitry Andric   typedef negative_binomial_distribution<_IntType> _Eng;
1404824e7fdSDimitry Andric   typedef typename _Eng::result_type result_type;
1414824e7fdSDimitry Andric   typedef typename _Eng::param_type param_type;
1424824e7fdSDimitry Andric   __save_flags<_CharT, _Traits> __lx(__is);
1434824e7fdSDimitry Andric   typedef basic_istream<_CharT, _Traits> _Istream;
1444824e7fdSDimitry Andric   __is.flags(_Istream::dec | _Istream::skipws);
1454824e7fdSDimitry Andric   result_type __k;
1464824e7fdSDimitry Andric   double __p;
1474824e7fdSDimitry Andric   __is >> __k >> __p;
1484824e7fdSDimitry Andric   if (!__is.fail())
1494824e7fdSDimitry Andric     __x.param(param_type(__k, __p));
1504824e7fdSDimitry Andric   return __is;
1514824e7fdSDimitry Andric }
1524824e7fdSDimitry Andric 
1534824e7fdSDimitry Andric _LIBCPP_END_NAMESPACE_STD
1544824e7fdSDimitry Andric 
1554824e7fdSDimitry Andric _LIBCPP_POP_MACROS
1564824e7fdSDimitry Andric 
1574824e7fdSDimitry Andric #endif // _LIBCPP___RANDOM_NEGATIVE_BINOMIAL_DISTRIBUTION_H
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