diff options
Diffstat (limited to 'contrib/llvm-project/libcxx/include/__random/poisson_distribution.h')
| -rw-r--r-- | contrib/llvm-project/libcxx/include/__random/poisson_distribution.h | 241 |
1 files changed, 241 insertions, 0 deletions
diff --git a/contrib/llvm-project/libcxx/include/__random/poisson_distribution.h b/contrib/llvm-project/libcxx/include/__random/poisson_distribution.h new file mode 100644 index 000000000000..61a092ef9dd4 --- /dev/null +++ b/contrib/llvm-project/libcxx/include/__random/poisson_distribution.h @@ -0,0 +1,241 @@ +//===----------------------------------------------------------------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// + +#ifndef _LIBCPP___RANDOM_POISSON_DISTRIBUTION_H +#define _LIBCPP___RANDOM_POISSON_DISTRIBUTION_H + +#include <__config> +#include <__random/clamp_to_integral.h> +#include <__random/exponential_distribution.h> +#include <__random/is_valid.h> +#include <__random/normal_distribution.h> +#include <__random/uniform_real_distribution.h> +#include <cmath> +#include <iosfwd> +#include <limits> + +#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) +# pragma GCC system_header +#endif + +_LIBCPP_PUSH_MACROS +#include <__undef_macros> + +_LIBCPP_BEGIN_NAMESPACE_STD + +template <class _IntType = int> +class _LIBCPP_TEMPLATE_VIS poisson_distribution { + static_assert(__libcpp_random_is_valid_inttype<_IntType>::value, "IntType must be a supported integer type"); + +public: + // types + typedef _IntType result_type; + + class _LIBCPP_TEMPLATE_VIS param_type { + double __mean_; + double __s_; + double __d_; + double __l_; + double __omega_; + double __c0_; + double __c1_; + double __c2_; + double __c3_; + double __c_; + + public: + typedef poisson_distribution distribution_type; + + _LIBCPP_HIDE_FROM_ABI explicit param_type(double __mean = 1.0); + + _LIBCPP_HIDE_FROM_ABI double mean() const { return __mean_; } + + friend _LIBCPP_HIDE_FROM_ABI bool operator==(const param_type& __x, const param_type& __y) { + return __x.__mean_ == __y.__mean_; + } + friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const param_type& __x, const param_type& __y) { return !(__x == __y); } + + friend class poisson_distribution; + }; + +private: + param_type __p_; + +public: + // constructors and reset functions +#ifndef _LIBCPP_CXX03_LANG + _LIBCPP_HIDE_FROM_ABI poisson_distribution() : poisson_distribution(1.0) {} + _LIBCPP_HIDE_FROM_ABI explicit poisson_distribution(double __mean) : __p_(__mean) {} +#else + _LIBCPP_HIDE_FROM_ABI explicit poisson_distribution(double __mean = 1.0) : __p_(__mean) {} +#endif + _LIBCPP_HIDE_FROM_ABI explicit poisson_distribution(const param_type& __p) : __p_(__p) {} + _LIBCPP_HIDE_FROM_ABI void reset() {} + + // generating functions + template <class _URNG> + _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) { + return (*this)(__g, __p_); + } + template <class _URNG> + _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p); + + // property functions + _LIBCPP_HIDE_FROM_ABI double mean() const { return __p_.mean(); } + + _LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; } + _LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; } + + _LIBCPP_HIDE_FROM_ABI result_type min() const { return 0; } + _LIBCPP_HIDE_FROM_ABI result_type max() const { return numeric_limits<result_type>::max(); } + + friend _LIBCPP_HIDE_FROM_ABI bool operator==(const poisson_distribution& __x, const poisson_distribution& __y) { + return __x.__p_ == __y.__p_; + } + friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const poisson_distribution& __x, const poisson_distribution& __y) { + return !(__x == __y); + } +}; + +template <class _IntType> +poisson_distribution<_IntType>::param_type::param_type(double __mean) + // According to the standard `inf` is a valid input, but it causes the + // distribution to hang, so we replace it with the maximum representable + // mean. + : __mean_(isinf(__mean) ? numeric_limits<double>::max() : __mean) { + if (__mean_ < 10) { + __s_ = 0; + __d_ = 0; + __l_ = std::exp(-__mean_); + __omega_ = 0; + __c3_ = 0; + __c2_ = 0; + __c1_ = 0; + __c0_ = 0; + __c_ = 0; + } else { + __s_ = std::sqrt(__mean_); + __d_ = 6 * __mean_ * __mean_; + __l_ = std::trunc(__mean_ - 1.1484); + __omega_ = .3989423 / __s_; + double __b1 = .4166667E-1 / __mean_; + double __b2 = .3 * __b1 * __b1; + __c3_ = .1428571 * __b1 * __b2; + __c2_ = __b2 - 15. * __c3_; + __c1_ = __b1 - 6. * __b2 + 45. * __c3_; + __c0_ = 1. - __b1 + 3. * __b2 - 15. * __c3_; + __c_ = .1069 / __mean_; + } +} + +template <class _IntType> +template <class _URNG> +_IntType poisson_distribution<_IntType>::operator()(_URNG& __urng, const param_type& __pr) { + static_assert(__libcpp_random_is_valid_urng<_URNG>::value, ""); + double __tx; + uniform_real_distribution<double> __urd; + if (__pr.__mean_ < 10) { + __tx = 0; + for (double __p = __urd(__urng); __p > __pr.__l_; ++__tx) + __p *= __urd(__urng); + } else { + double __difmuk; + double __g = __pr.__mean_ + __pr.__s_ * normal_distribution<double>()(__urng); + double __u; + if (__g > 0) { + __tx = std::trunc(__g); + if (__tx >= __pr.__l_) + return std::__clamp_to_integral<result_type>(__tx); + __difmuk = __pr.__mean_ - __tx; + __u = __urd(__urng); + if (__pr.__d_ * __u >= __difmuk * __difmuk * __difmuk) + return std::__clamp_to_integral<result_type>(__tx); + } + exponential_distribution<double> __edist; + for (bool __using_exp_dist = false; true; __using_exp_dist = true) { + double __e; + if (__using_exp_dist || __g <= 0) { + double __t; + do { + __e = __edist(__urng); + __u = __urd(__urng); + __u += __u - 1; + __t = 1.8 + (__u < 0 ? -__e : __e); + } while (__t <= -.6744); + __tx = std::trunc(__pr.__mean_ + __pr.__s_ * __t); + __difmuk = __pr.__mean_ - __tx; + __using_exp_dist = true; + } + double __px; + double __py; + if (__tx < 10 && __tx >= 0) { + const double __fac[] = {1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880}; + __px = -__pr.__mean_; + __py = std::pow(__pr.__mean_, (double)__tx) / __fac[static_cast<int>(__tx)]; + } else { + double __del = .8333333E-1 / __tx; + __del -= 4.8 * __del * __del * __del; + double __v = __difmuk / __tx; + if (std::abs(__v) > 0.25) + __px = __tx * std::log(1 + __v) - __difmuk - __del; + else + __px = __tx * __v * __v * + (((((((.1250060 * __v + -.1384794) * __v + .1421878) * __v + -.1661269) * __v + .2000118) * __v + + -.2500068) * + __v + + .3333333) * + __v + + -.5) - + __del; + __py = .3989423 / std::sqrt(__tx); + } + double __r = (0.5 - __difmuk) / __pr.__s_; + double __r2 = __r * __r; + double __fx = -0.5 * __r2; + double __fy = __pr.__omega_ * (((__pr.__c3_ * __r2 + __pr.__c2_) * __r2 + __pr.__c1_) * __r2 + __pr.__c0_); + if (__using_exp_dist) { + if (__pr.__c_ * std::abs(__u) <= __py * std::exp(__px + __e) - __fy * std::exp(__fx + __e)) + break; + } else { + if (__fy - __u * __fy <= __py * std::exp(__px - __fx)) + break; + } + } + } + return std::__clamp_to_integral<result_type>(__tx); +} + +template <class _CharT, class _Traits, class _IntType> +_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>& +operator<<(basic_ostream<_CharT, _Traits>& __os, const poisson_distribution<_IntType>& __x) { + __save_flags<_CharT, _Traits> __lx(__os); + typedef basic_ostream<_CharT, _Traits> _OStream; + __os.flags(_OStream::dec | _OStream::left | _OStream::fixed | _OStream::scientific); + return __os << __x.mean(); +} + +template <class _CharT, class _Traits, class _IntType> +_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>& +operator>>(basic_istream<_CharT, _Traits>& __is, poisson_distribution<_IntType>& __x) { + typedef poisson_distribution<_IntType> _Eng; + typedef typename _Eng::param_type param_type; + __save_flags<_CharT, _Traits> __lx(__is); + typedef basic_istream<_CharT, _Traits> _Istream; + __is.flags(_Istream::dec | _Istream::skipws); + double __mean; + __is >> __mean; + if (!__is.fail()) + __x.param(param_type(__mean)); + return __is; +} + +_LIBCPP_END_NAMESPACE_STD + +_LIBCPP_POP_MACROS + +#endif // _LIBCPP___RANDOM_POISSON_DISTRIBUTION_H |