1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
|
//===----------------------------------------------------------------------===//
//
// 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_BINOMIAL_DISTRIBUTION_H
#define _LIBCPP___RANDOM_BINOMIAL_DISTRIBUTION_H
#include <__config>
#include <__random/is_valid.h>
#include <__random/uniform_real_distribution.h>
#include <cmath>
#include <iosfwd>
#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 binomial_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
{
result_type __t_;
double __p_;
double __pr_;
double __odds_ratio_;
result_type __r0_;
public:
typedef binomial_distribution distribution_type;
explicit param_type(result_type __t = 1, double __p = 0.5);
_LIBCPP_INLINE_VISIBILITY
result_type t() const {return __t_;}
_LIBCPP_INLINE_VISIBILITY
double p() const {return __p_;}
friend _LIBCPP_INLINE_VISIBILITY
bool operator==(const param_type& __x, const param_type& __y)
{return __x.__t_ == __y.__t_ && __x.__p_ == __y.__p_;}
friend _LIBCPP_INLINE_VISIBILITY
bool operator!=(const param_type& __x, const param_type& __y)
{return !(__x == __y);}
friend class binomial_distribution;
};
private:
param_type __p_;
public:
// constructors and reset functions
#ifndef _LIBCPP_CXX03_LANG
_LIBCPP_INLINE_VISIBILITY
binomial_distribution() : binomial_distribution(1) {}
_LIBCPP_INLINE_VISIBILITY
explicit binomial_distribution(result_type __t, double __p = 0.5)
: __p_(param_type(__t, __p)) {}
#else
_LIBCPP_INLINE_VISIBILITY
explicit binomial_distribution(result_type __t = 1, double __p = 0.5)
: __p_(param_type(__t, __p)) {}
#endif
_LIBCPP_INLINE_VISIBILITY
explicit binomial_distribution(const param_type& __p) : __p_(__p) {}
_LIBCPP_INLINE_VISIBILITY
void reset() {}
// generating functions
template<class _URNG>
_LIBCPP_INLINE_VISIBILITY
result_type operator()(_URNG& __g)
{return (*this)(__g, __p_);}
template<class _URNG> result_type operator()(_URNG& __g, const param_type& __p);
// property functions
_LIBCPP_INLINE_VISIBILITY
result_type t() const {return __p_.t();}
_LIBCPP_INLINE_VISIBILITY
double p() const {return __p_.p();}
_LIBCPP_INLINE_VISIBILITY
param_type param() const {return __p_;}
_LIBCPP_INLINE_VISIBILITY
void param(const param_type& __p) {__p_ = __p;}
_LIBCPP_INLINE_VISIBILITY
result_type min() const {return 0;}
_LIBCPP_INLINE_VISIBILITY
result_type max() const {return t();}
friend _LIBCPP_INLINE_VISIBILITY
bool operator==(const binomial_distribution& __x,
const binomial_distribution& __y)
{return __x.__p_ == __y.__p_;}
friend _LIBCPP_INLINE_VISIBILITY
bool operator!=(const binomial_distribution& __x,
const binomial_distribution& __y)
{return !(__x == __y);}
};
#ifndef _LIBCPP_MSVCRT_LIKE
extern "C" double lgamma_r(double, int *);
#endif
inline _LIBCPP_INLINE_VISIBILITY double __libcpp_lgamma(double __d) {
#if defined(_LIBCPP_MSVCRT_LIKE)
return lgamma(__d);
#else
int __sign;
return lgamma_r(__d, &__sign);
#endif
}
template<class _IntType>
binomial_distribution<_IntType>::param_type::param_type(result_type __t, double __p)
: __t_(__t), __p_(__p)
{
if (0 < __p_ && __p_ < 1)
{
__r0_ = static_cast<result_type>((__t_ + 1) * __p_);
__pr_ = _VSTD::exp(__libcpp_lgamma(__t_ + 1.) -
__libcpp_lgamma(__r0_ + 1.) -
__libcpp_lgamma(__t_ - __r0_ + 1.) + __r0_ * _VSTD::log(__p_) +
(__t_ - __r0_) * _VSTD::log(1 - __p_));
__odds_ratio_ = __p_ / (1 - __p_);
}
}
// Reference: Kemp, C.D. (1986). `A modal method for generating binomial
// variables', Commun. Statist. - Theor. Meth. 15(3), 805-813.
template<class _IntType>
template<class _URNG>
_IntType
binomial_distribution<_IntType>::operator()(_URNG& __g, const param_type& __pr)
{
static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
if (__pr.__t_ == 0 || __pr.__p_ == 0)
return 0;
if (__pr.__p_ == 1)
return __pr.__t_;
uniform_real_distribution<double> __gen;
double __u = __gen(__g) - __pr.__pr_;
if (__u < 0)
return __pr.__r0_;
double __pu = __pr.__pr_;
double __pd = __pu;
result_type __ru = __pr.__r0_;
result_type __rd = __ru;
while (true)
{
bool __break = true;
if (__rd >= 1)
{
__pd *= __rd / (__pr.__odds_ratio_ * (__pr.__t_ - __rd + 1));
__u -= __pd;
__break = false;
if (__u < 0)
return __rd - 1;
}
if ( __rd != 0 )
--__rd;
++__ru;
if (__ru <= __pr.__t_)
{
__pu *= (__pr.__t_ - __ru + 1) * __pr.__odds_ratio_ / __ru;
__u -= __pu;
__break = false;
if (__u < 0)
return __ru;
}
if (__break)
return 0;
}
}
template <class _CharT, class _Traits, class _IntType>
_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os,
const binomial_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);
_CharT __sp = __os.widen(' ');
__os.fill(__sp);
return __os << __x.t() << __sp << __x.p();
}
template <class _CharT, class _Traits, class _IntType>
_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
operator>>(basic_istream<_CharT, _Traits>& __is,
binomial_distribution<_IntType>& __x)
{
typedef binomial_distribution<_IntType> _Eng;
typedef typename _Eng::result_type result_type;
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);
result_type __t;
double __p;
__is >> __t >> __p;
if (!__is.fail())
__x.param(param_type(__t, __p));
return __is;
}
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP___RANDOM_BINOMIAL_DISTRIBUTION_H
|
