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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 <__cstddef/ptrdiff_t.h>
15#include <__random/is_valid.h>
16#include <__random/uniform_real_distribution.h>
17#include <__vector/comparison.h>
18#include <__vector/vector.h>
19#include <cmath>
20#include <initializer_list>
21#include <iosfwd>
22
23#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
24# pragma GCC system_header
25#endif
26
27_LIBCPP_PUSH_MACROS
28#include <__undef_macros>
29
30_LIBCPP_BEGIN_NAMESPACE_STD
31
32template <class _RealType = double>
33class piecewise_linear_distribution {
34 static_assert(__libcpp_random_is_valid_realtype<_RealType>::value,
35 "RealType must be a supported floating-point type");
36
37public:
38 // types
39 typedef _RealType result_type;
40
41 class param_type {
42 vector<result_type> __b_;
43 vector<result_type> __densities_;
44 vector<result_type> __areas_;
45
46 public:
47 typedef piecewise_linear_distribution distribution_type;
48
49 _LIBCPP_HIDE_FROM_ABI param_type();
50 template <class _InputIteratorB, class _InputIteratorW>
51 _LIBCPP_HIDE_FROM_ABI param_type(_InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w);
52#ifndef _LIBCPP_CXX03_LANG
53 template <class _UnaryOperation>
54 _LIBCPP_HIDE_FROM_ABI param_type(initializer_list<result_type> __bl, _UnaryOperation __fw);
55#endif // _LIBCPP_CXX03_LANG
56 template <class _UnaryOperation>
57 _LIBCPP_HIDE_FROM_ABI param_type(size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw);
58 _LIBCPP_HIDE_FROM_ABI param_type(param_type const&) = default;
59 _LIBCPP_HIDE_FROM_ABI param_type& operator=(const param_type& __rhs);
60
61 _LIBCPP_HIDE_FROM_ABI vector<result_type> intervals() const { return __b_; }
62 _LIBCPP_HIDE_FROM_ABI vector<result_type> densities() const { return __densities_; }
63
64 friend _LIBCPP_HIDE_FROM_ABI bool operator==(const param_type& __x, const param_type& __y) {
65 return __x.__densities_ == __y.__densities_ && __x.__b_ == __y.__b_;
66 }
67 friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const param_type& __x, const param_type& __y) { return !(__x == __y); }
68
69 private:
70 _LIBCPP_HIDE_FROM_ABI void __init();
71
72 friend class piecewise_linear_distribution;
73
74 template <class _CharT, class _Traits, class _RT>
75 friend basic_ostream<_CharT, _Traits>&
76 operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_linear_distribution<_RT>& __x);
77
78 template <class _CharT, class _Traits, class _RT>
79 friend basic_istream<_CharT, _Traits>&
80 operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_linear_distribution<_RT>& __x);
81 };
82
83private:
84 param_type __p_;
85
86public:
87 // constructor and reset functions
88 _LIBCPP_HIDE_FROM_ABI piecewise_linear_distribution() {}
89 template <class _InputIteratorB, class _InputIteratorW>
90 _LIBCPP_HIDE_FROM_ABI
91 piecewise_linear_distribution(_InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w)
92 : __p_(__f_b, __l_b, __f_w) {}
93
94#ifndef _LIBCPP_CXX03_LANG
95 template <class _UnaryOperation>
96 _LIBCPP_HIDE_FROM_ABI piecewise_linear_distribution(initializer_list<result_type> __bl, _UnaryOperation __fw)
97 : __p_(__bl, __fw) {}
98#endif // _LIBCPP_CXX03_LANG
99
100 template <class _UnaryOperation>
101 _LIBCPP_HIDE_FROM_ABI
102 piecewise_linear_distribution(size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw)
103 : __p_(__nw, __xmin, __xmax, __fw) {}
104
105 _LIBCPP_HIDE_FROM_ABI explicit piecewise_linear_distribution(const param_type& __p) : __p_(__p) {}
106
107 _LIBCPP_HIDE_FROM_ABI void reset() {}
108
109 // generating functions
110 template <class _URNG>
111 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) {
112 return (*this)(__g, __p_);
113 }
114 template <class _URNG>
115 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);
116
117 // property functions
118 _LIBCPP_HIDE_FROM_ABI vector<result_type> intervals() const { return __p_.intervals(); }
119 _LIBCPP_HIDE_FROM_ABI vector<result_type> densities() const { return __p_.densities(); }
120
121 _LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; }
122 _LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; }
123
124 _LIBCPP_HIDE_FROM_ABI result_type min() const { return __p_.__b_.front(); }
125 _LIBCPP_HIDE_FROM_ABI result_type max() const { return __p_.__b_.back(); }
126
127 friend _LIBCPP_HIDE_FROM_ABI bool
128 operator==(const piecewise_linear_distribution& __x, const piecewise_linear_distribution& __y) {
129 return __x.__p_ == __y.__p_;
130 }
131 friend _LIBCPP_HIDE_FROM_ABI bool
132 operator!=(const piecewise_linear_distribution& __x, const piecewise_linear_distribution& __y) {
133 return !(__x == __y);
134 }
135
136 template <class _CharT, class _Traits, class _RT>
137 friend basic_ostream<_CharT, _Traits>&
138 operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_linear_distribution<_RT>& __x);
139
140 template <class _CharT, class _Traits, class _RT>
141 friend basic_istream<_CharT, _Traits>&
142 operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_linear_distribution<_RT>& __x);
143};
144
145template <class _RealType>
146typename piecewise_linear_distribution<_RealType>::param_type&
147piecewise_linear_distribution<_RealType>::param_type::operator=(const param_type& __rhs) {
148 // These can throw
149 __b_.reserve(__rhs.__b_.size());
150 __densities_.reserve(__rhs.__densities_.size());
151 __areas_.reserve(__rhs.__areas_.size());
152
153 // These can not throw
154 __b_ = __rhs.__b_;
155 __densities_ = __rhs.__densities_;
156 __areas_ = __rhs.__areas_;
157 return *this;
158}
159
160template <class _RealType>
161void piecewise_linear_distribution<_RealType>::param_type::__init() {
162 __areas_.assign(__densities_.size() - 1, result_type());
163 result_type __sp = 0;
164 for (size_t __i = 0; __i < __areas_.size(); ++__i) {
165 __areas_[__i] = (__densities_[__i + 1] + __densities_[__i]) * (__b_[__i + 1] - __b_[__i]) * .5;
166 __sp += __areas_[__i];
167 }
168 for (size_t __i = __areas_.size(); __i > 1;) {
169 --__i;
170 __areas_[__i] = __areas_[__i - 1] / __sp;
171 }
172 __areas_[0] = 0;
173 for (size_t __i = 1; __i < __areas_.size(); ++__i)
174 __areas_[__i] += __areas_[__i - 1];
175 for (size_t __i = 0; __i < __densities_.size(); ++__i)
176 __densities_[__i] /= __sp;
177}
178
179template <class _RealType>
180piecewise_linear_distribution<_RealType>::param_type::param_type() : __b_(2), __densities_(2, 1.0), __areas_(1, 0.0) {
181 __b_[1] = 1;
182}
183
184template <class _RealType>
185template <class _InputIteratorB, class _InputIteratorW>
186piecewise_linear_distribution<_RealType>::param_type::param_type(
187 _InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w)
188 : __b_(__f_b, __l_b) {
189 if (__b_.size() < 2) {
190 __b_.resize(2);
191 __b_[0] = 0;
192 __b_[1] = 1;
193 __densities_.assign(2, 1.0);
194 __areas_.assign(1, 0.0);
195 } else {
196 __densities_.reserve(__b_.size());
197 for (size_t __i = 0; __i < __b_.size(); ++__i, ++__f_w)
198 __densities_.push_back(*__f_w);
199 __init();
200 }
201}
202
203#ifndef _LIBCPP_CXX03_LANG
204
205template <class _RealType>
206template <class _UnaryOperation>
207piecewise_linear_distribution<_RealType>::param_type::param_type(
208 initializer_list<result_type> __bl, _UnaryOperation __fw)
209 : __b_(__bl.begin(), __bl.end()) {
210 if (__b_.size() < 2) {
211 __b_.resize(2);
212 __b_[0] = 0;
213 __b_[1] = 1;
214 __densities_.assign(2, 1.0);
215 __areas_.assign(1, 0.0);
216 } else {
217 __densities_.reserve(__b_.size());
218 for (size_t __i = 0; __i < __b_.size(); ++__i)
219 __densities_.push_back(__fw(__b_[__i]));
220 __init();
221 }
222}
223
224#endif // _LIBCPP_CXX03_LANG
225
226template <class _RealType>
227template <class _UnaryOperation>
228piecewise_linear_distribution<_RealType>::param_type::param_type(
229 size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw)
230 : __b_(__nw == 0 ? 2 : __nw + 1) {
231 size_t __n = __b_.size() - 1;
232 result_type __d = (__xmax - __xmin) / __n;
233 __densities_.reserve(__b_.size());
234 for (size_t __i = 0; __i < __n; ++__i) {
235 __b_[__i] = __xmin + __i * __d;
236 __densities_.push_back(__fw(__b_[__i]));
237 }
238 __b_[__n] = __xmax;
239 __densities_.push_back(__fw(__b_[__n]));
240 __init();
241}
242
243template <class _RealType>
244template <class _URNG>
245_RealType piecewise_linear_distribution<_RealType>::operator()(_URNG& __g, const param_type& __p) {
246 static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
247 typedef uniform_real_distribution<result_type> _Gen;
248 result_type __u = _Gen()(__g);
249 ptrdiff_t __k = std::upper_bound(__p.__areas_.begin(), __p.__areas_.end(), __u) - __p.__areas_.begin() - 1;
250 __u -= __p.__areas_[__k];
251 const result_type __dk = __p.__densities_[__k];
252 const result_type __dk1 = __p.__densities_[__k + 1];
253 const result_type __deltad = __dk1 - __dk;
254 const result_type __bk = __p.__b_[__k];
255 if (__deltad == 0)
256 return __u / __dk + __bk;
257 const result_type __bk1 = __p.__b_[__k + 1];
258 const result_type __deltab = __bk1 - __bk;
259 return (__bk * __dk1 - __bk1 * __dk + std::sqrt(__deltab * (__deltab * __dk * __dk + 2 * __deltad * __u))) / __deltad;
260}
261
262template <class _CharT, class _Traits, class _RT>
263_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
264operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_linear_distribution<_RT>& __x) {
265 __save_flags<_CharT, _Traits> __lx(__os);
266 typedef basic_ostream<_CharT, _Traits> _OStream;
267 __os.flags(_OStream::dec | _OStream::left | _OStream::fixed | _OStream::scientific);
268 _CharT __sp = __os.widen(' ');
269 __os.fill(__sp);
270 size_t __n = __x.__p_.__b_.size();
271 __os << __n;
272 for (size_t __i = 0; __i < __n; ++__i)
273 __os << __sp << __x.__p_.__b_[__i];
274 __n = __x.__p_.__densities_.size();
275 __os << __sp << __n;
276 for (size_t __i = 0; __i < __n; ++__i)
277 __os << __sp << __x.__p_.__densities_[__i];
278 __n = __x.__p_.__areas_.size();
279 __os << __sp << __n;
280 for (size_t __i = 0; __i < __n; ++__i)
281 __os << __sp << __x.__p_.__areas_[__i];
282 return __os;
283}
284
285template <class _CharT, class _Traits, class _RT>
286_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
287operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_linear_distribution<_RT>& __x) {
288 typedef piecewise_linear_distribution<_RT> _Eng;
289 typedef typename _Eng::result_type result_type;
290 __save_flags<_CharT, _Traits> __lx(__is);
291 typedef basic_istream<_CharT, _Traits> _Istream;
292 __is.flags(_Istream::dec | _Istream::skipws);
293 size_t __n;
294 __is >> __n;
295 vector<result_type> __b(__n);
296 for (size_t __i = 0; __i < __n; ++__i)
297 __is >> __b[__i];
298 __is >> __n;
299 vector<result_type> __densities(__n);
300 for (size_t __i = 0; __i < __n; ++__i)
301 __is >> __densities[__i];
302 __is >> __n;
303 vector<result_type> __areas(__n);
304 for (size_t __i = 0; __i < __n; ++__i)
305 __is >> __areas[__i];
306 if (!__is.fail()) {
307 swap(__x.__p_.__b_, __b);
308 swap(__x.__p_.__densities_, __densities);
309 swap(__x.__p_.__areas_, __areas);
310 }
311 return __is;
312}
313
314_LIBCPP_END_NAMESPACE_STD
315
316_LIBCPP_POP_MACROS
317
318#endif // _LIBCPP___RANDOM_PIECEWISE_LINEAR_DISTRIBUTION_H