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_PIECEWISE_LINEAR_DISTRIBUTION_H
10#define _LIBCPP___RANDOM_PIECEWISE_LINEAR_DISTRIBUTION_H
11
12#include <__algorithm/upper_bound.h>
13#include <__config>
14#include <__random/is_valid.h>
15#include <__random/uniform_real_distribution.h>
16#include <cmath>
17#include <iosfwd>
18#include <vector>
19
20#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
21# pragma GCC system_header
22#endif
23
24_LIBCPP_PUSH_MACROS
25#include <__undef_macros>
26
27_LIBCPP_BEGIN_NAMESPACE_STD
28
29template <class _RealType = double>
30class _LIBCPP_TEMPLATE_VIS piecewise_linear_distribution {
31 static_assert(__libcpp_random_is_valid_realtype<_RealType>::value,
32 "RealType must be a supported floating-point type");
33
34public:
35 // types
36 typedef _RealType result_type;
37
38 class _LIBCPP_TEMPLATE_VIS param_type {
39 vector<result_type> __b_;
40 vector<result_type> __densities_;
41 vector<result_type> __areas_;
42
43 public:
44 typedef piecewise_linear_distribution distribution_type;
45
46 _LIBCPP_HIDE_FROM_ABI param_type();
47 template <class _InputIteratorB, class _InputIteratorW>
48 _LIBCPP_HIDE_FROM_ABI param_type(_InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w);
49#ifndef _LIBCPP_CXX03_LANG
50 template <class _UnaryOperation>
51 _LIBCPP_HIDE_FROM_ABI param_type(initializer_list<result_type> __bl, _UnaryOperation __fw);
52#endif // _LIBCPP_CXX03_LANG
53 template <class _UnaryOperation>
54 _LIBCPP_HIDE_FROM_ABI param_type(size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw);
55 _LIBCPP_HIDE_FROM_ABI param_type(param_type const&) = default;
56 _LIBCPP_HIDE_FROM_ABI param_type& operator=(const param_type& __rhs);
57
58 _LIBCPP_HIDE_FROM_ABI vector<result_type> intervals() const { return __b_; }
59 _LIBCPP_HIDE_FROM_ABI vector<result_type> densities() const { return __densities_; }
60
61 friend _LIBCPP_HIDE_FROM_ABI bool operator==(const param_type& __x, const param_type& __y) {
62 return __x.__densities_ == __y.__densities_ && __x.__b_ == __y.__b_;
63 }
64 friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const param_type& __x, const param_type& __y) { return !(__x == __y); }
65
66 private:
67 _LIBCPP_HIDE_FROM_ABI void __init();
68
69 friend class piecewise_linear_distribution;
70
71 template <class _CharT, class _Traits, class _RT>
72 friend basic_ostream<_CharT, _Traits>&
73 operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_linear_distribution<_RT>& __x);
74
75 template <class _CharT, class _Traits, class _RT>
76 friend basic_istream<_CharT, _Traits>&
77 operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_linear_distribution<_RT>& __x);
78 };
79
80private:
81 param_type __p_;
82
83public:
84 // constructor and reset functions
85 _LIBCPP_HIDE_FROM_ABI piecewise_linear_distribution() {}
86 template <class _InputIteratorB, class _InputIteratorW>
87 _LIBCPP_HIDE_FROM_ABI
88 piecewise_linear_distribution(_InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w)
89 : __p_(__f_b, __l_b, __f_w) {}
90
91#ifndef _LIBCPP_CXX03_LANG
92 template <class _UnaryOperation>
93 _LIBCPP_HIDE_FROM_ABI piecewise_linear_distribution(initializer_list<result_type> __bl, _UnaryOperation __fw)
94 : __p_(__bl, __fw) {}
95#endif // _LIBCPP_CXX03_LANG
96
97 template <class _UnaryOperation>
98 _LIBCPP_HIDE_FROM_ABI
99 piecewise_linear_distribution(size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw)
100 : __p_(__nw, __xmin, __xmax, __fw) {}
101
102 _LIBCPP_HIDE_FROM_ABI explicit piecewise_linear_distribution(const param_type& __p) : __p_(__p) {}
103
104 _LIBCPP_HIDE_FROM_ABI void reset() {}
105
106 // generating functions
107 template <class _URNG>
108 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) {
109 return (*this)(__g, __p_);
110 }
111 template <class _URNG>
112 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);
113
114 // property functions
115 _LIBCPP_HIDE_FROM_ABI vector<result_type> intervals() const { return __p_.intervals(); }
116 _LIBCPP_HIDE_FROM_ABI vector<result_type> densities() const { return __p_.densities(); }
117
118 _LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; }
119 _LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; }
120
121 _LIBCPP_HIDE_FROM_ABI result_type min() const { return __p_.__b_.front(); }
122 _LIBCPP_HIDE_FROM_ABI result_type max() const { return __p_.__b_.back(); }
123
124 friend _LIBCPP_HIDE_FROM_ABI bool
125 operator==(const piecewise_linear_distribution& __x, const piecewise_linear_distribution& __y) {
126 return __x.__p_ == __y.__p_;
127 }
128 friend _LIBCPP_HIDE_FROM_ABI bool
129 operator!=(const piecewise_linear_distribution& __x, const piecewise_linear_distribution& __y) {
130 return !(__x == __y);
131 }
132
133 template <class _CharT, class _Traits, class _RT>
134 friend basic_ostream<_CharT, _Traits>&
135 operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_linear_distribution<_RT>& __x);
136
137 template <class _CharT, class _Traits, class _RT>
138 friend basic_istream<_CharT, _Traits>&
139 operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_linear_distribution<_RT>& __x);
140};
141
142template <class _RealType>
143typename piecewise_linear_distribution<_RealType>::param_type&
144piecewise_linear_distribution<_RealType>::param_type::operator=(const param_type& __rhs) {
145 // These can throw
146 __b_.reserve(__rhs.__b_.size());
147 __densities_.reserve(__rhs.__densities_.size());
148 __areas_.reserve(__rhs.__areas_.size());
149
150 // These can not throw
151 __b_ = __rhs.__b_;
152 __densities_ = __rhs.__densities_;
153 __areas_ = __rhs.__areas_;
154 return *this;
155}
156
157template <class _RealType>
158void piecewise_linear_distribution<_RealType>::param_type::__init() {
159 __areas_.assign(__densities_.size() - 1, result_type());
160 result_type __sp = 0;
161 for (size_t __i = 0; __i < __areas_.size(); ++__i) {
162 __areas_[__i] = (__densities_[__i + 1] + __densities_[__i]) * (__b_[__i + 1] - __b_[__i]) * .5;
163 __sp += __areas_[__i];
164 }
165 for (size_t __i = __areas_.size(); __i > 1;) {
166 --__i;
167 __areas_[__i] = __areas_[__i - 1] / __sp;
168 }
169 __areas_[0] = 0;
170 for (size_t __i = 1; __i < __areas_.size(); ++__i)
171 __areas_[__i] += __areas_[__i - 1];
172 for (size_t __i = 0; __i < __densities_.size(); ++__i)
173 __densities_[__i] /= __sp;
174}
175
176template <class _RealType>
177piecewise_linear_distribution<_RealType>::param_type::param_type() : __b_(2), __densities_(2, 1.0), __areas_(1, 0.0) {
178 __b_[1] = 1;
179}
180
181template <class _RealType>
182template <class _InputIteratorB, class _InputIteratorW>
183piecewise_linear_distribution<_RealType>::param_type::param_type(
184 _InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w)
185 : __b_(__f_b, __l_b) {
186 if (__b_.size() < 2) {
187 __b_.resize(2);
188 __b_[0] = 0;
189 __b_[1] = 1;
190 __densities_.assign(2, 1.0);
191 __areas_.assign(1, 0.0);
192 } else {
193 __densities_.reserve(__b_.size());
194 for (size_t __i = 0; __i < __b_.size(); ++__i, ++__f_w)
195 __densities_.push_back(*__f_w);
196 __init();
197 }
198}
199
200#ifndef _LIBCPP_CXX03_LANG
201
202template <class _RealType>
203template <class _UnaryOperation>
204piecewise_linear_distribution<_RealType>::param_type::param_type(
205 initializer_list<result_type> __bl, _UnaryOperation __fw)
206 : __b_(__bl.begin(), __bl.end()) {
207 if (__b_.size() < 2) {
208 __b_.resize(2);
209 __b_[0] = 0;
210 __b_[1] = 1;
211 __densities_.assign(2, 1.0);
212 __areas_.assign(1, 0.0);
213 } else {
214 __densities_.reserve(__b_.size());
215 for (size_t __i = 0; __i < __b_.size(); ++__i)
216 __densities_.push_back(__fw(__b_[__i]));
217 __init();
218 }
219}
220
221#endif // _LIBCPP_CXX03_LANG
222
223template <class _RealType>
224template <class _UnaryOperation>
225piecewise_linear_distribution<_RealType>::param_type::param_type(
226 size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw)
227 : __b_(__nw == 0 ? 2 : __nw + 1) {
228 size_t __n = __b_.size() - 1;
229 result_type __d = (__xmax - __xmin) / __n;
230 __densities_.reserve(__b_.size());
231 for (size_t __i = 0; __i < __n; ++__i) {
232 __b_[__i] = __xmin + __i * __d;
233 __densities_.push_back(__fw(__b_[__i]));
234 }
235 __b_[__n] = __xmax;
236 __densities_.push_back(__fw(__b_[__n]));
237 __init();
238}
239
240template <class _RealType>
241template <class _URNG>
242_RealType piecewise_linear_distribution<_RealType>::operator()(_URNG& __g, const param_type& __p) {
243 static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
244 typedef uniform_real_distribution<result_type> _Gen;
245 result_type __u = _Gen()(__g);
246 ptrdiff_t __k = std::upper_bound(__p.__areas_.begin(), __p.__areas_.end(), __u) - __p.__areas_.begin() - 1;
247 __u -= __p.__areas_[__k];
248 const result_type __dk = __p.__densities_[__k];
249 const result_type __dk1 = __p.__densities_[__k + 1];
250 const result_type __deltad = __dk1 - __dk;
251 const result_type __bk = __p.__b_[__k];
252 if (__deltad == 0)
253 return __u / __dk + __bk;
254 const result_type __bk1 = __p.__b_[__k + 1];
255 const result_type __deltab = __bk1 - __bk;
256 return (__bk * __dk1 - __bk1 * __dk + std::sqrt(__deltab * (__deltab * __dk * __dk + 2 * __deltad * __u))) / __deltad;
257}
258
259template <class _CharT, class _Traits, class _RT>
260_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
261operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_linear_distribution<_RT>& __x) {
262 __save_flags<_CharT, _Traits> __lx(__os);
263 typedef basic_ostream<_CharT, _Traits> _OStream;
264 __os.flags(_OStream::dec | _OStream::left | _OStream::fixed | _OStream::scientific);
265 _CharT __sp = __os.widen(' ');
266 __os.fill(__sp);
267 size_t __n = __x.__p_.__b_.size();
268 __os << __n;
269 for (size_t __i = 0; __i < __n; ++__i)
270 __os << __sp << __x.__p_.__b_[__i];
271 __n = __x.__p_.__densities_.size();
272 __os << __sp << __n;
273 for (size_t __i = 0; __i < __n; ++__i)
274 __os << __sp << __x.__p_.__densities_[__i];
275 __n = __x.__p_.__areas_.size();
276 __os << __sp << __n;
277 for (size_t __i = 0; __i < __n; ++__i)
278 __os << __sp << __x.__p_.__areas_[__i];
279 return __os;
280}
281
282template <class _CharT, class _Traits, class _RT>
283_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
284operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_linear_distribution<_RT>& __x) {
285 typedef piecewise_linear_distribution<_RT> _Eng;
286 typedef typename _Eng::result_type result_type;
287 __save_flags<_CharT, _Traits> __lx(__is);
288 typedef basic_istream<_CharT, _Traits> _Istream;
289 __is.flags(_Istream::dec | _Istream::skipws);
290 size_t __n;
291 __is >> __n;
292 vector<result_type> __b(__n);
293 for (size_t __i = 0; __i < __n; ++__i)
294 __is >> __b[__i];
295 __is >> __n;
296 vector<result_type> __densities(__n);
297 for (size_t __i = 0; __i < __n; ++__i)
298 __is >> __densities[__i];
299 __is >> __n;
300 vector<result_type> __areas(__n);
301 for (size_t __i = 0; __i < __n; ++__i)
302 __is >> __areas[__i];
303 if (!__is.fail()) {
304 swap(__x.__p_.__b_, __b);
305 swap(__x.__p_.__densities_, __densities);
306 swap(__x.__p_.__areas_, __areas);
307 }
308 return __is;
309}
310
311_LIBCPP_END_NAMESPACE_STD
312
313_LIBCPP_POP_MACROS
314
315#endif // _LIBCPP___RANDOM_PIECEWISE_LINEAR_DISTRIBUTION_H
316