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 158