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Issue 3050029: [gcc] GCC 4.5.0=>4.5.1 (Closed) Base URL: ssh://git@gitrw.chromium.org:9222/nacl-toolchain.git
Patch Set: Created 10 years, 4 months ago
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1 // random number generation -*- C++ -*-
2
3 // Copyright (C) 2007, 2008, 2009 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
9 // any later version.
10
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
15
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
19
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
24
25 /**
26 * @file tr1_impl/random
27 * This is an internal header file, included by other library headers.
28 * You should not attempt to use it directly.
29 */
30
31 namespace std
32 {
33 _GLIBCXX_BEGIN_NAMESPACE_TR1
34
35 // [5.1] Random number generation
36
37 /**
38 * @defgroup tr1_random Random Number Generation
39 * @ingroup numerics
40 * A facility for generating random numbers on selected distributions.
41 * @{
42 */
43
44 /*
45 * Implementation-space details.
46 */
47 namespace __detail
48 {
49 template<typename _UIntType, int __w,
50 bool = __w < std::numeric_limits<_UIntType>::digits>
51 struct _Shift
52 { static const _UIntType __value = 0; };
53
54 template<typename _UIntType, int __w>
55 struct _Shift<_UIntType, __w, true>
56 { static const _UIntType __value = _UIntType(1) << __w; };
57
58 template<typename _Tp, _Tp __a, _Tp __c, _Tp __m, bool>
59 struct _Mod;
60
61 // Dispatch based on modulus value to prevent divide-by-zero compile-time
62 // errors when m == 0.
63 template<typename _Tp, _Tp __a, _Tp __c, _Tp __m>
64 inline _Tp
65 __mod(_Tp __x)
66 { return _Mod<_Tp, __a, __c, __m, __m == 0>::__calc(__x); }
67
68 typedef __gnu_cxx::__conditional_type<(sizeof(unsigned) == 4),
69 unsigned, unsigned long>::__type _UInt32Type;
70
71 /*
72 * An adaptor class for converting the output of any Generator into
73 * the input for a specific Distribution.
74 */
75 template<typename _Engine, typename _Distribution>
76 struct _Adaptor
77 {
78 typedef typename remove_reference<_Engine>::type _BEngine;
79 typedef typename _BEngine::result_type _Engine_result_type;
80 typedef typename _Distribution::input_type result_type;
81
82 public:
83 _Adaptor(const _Engine& __g)
84 : _M_g(__g) { }
85
86 result_type
87 min() const
88 {
89 result_type __return_value;
90 if (is_integral<_Engine_result_type>::value
91 && is_integral<result_type>::value)
92 __return_value = _M_g.min();
93 else
94 __return_value = result_type(0);
95 return __return_value;
96 }
97
98 result_type
99 max() const
100 {
101 result_type __return_value;
102 if (is_integral<_Engine_result_type>::value
103 && is_integral<result_type>::value)
104 __return_value = _M_g.max();
105 else if (!is_integral<result_type>::value)
106 __return_value = result_type(1);
107 else
108 __return_value = std::numeric_limits<result_type>::max() - 1;
109 return __return_value;
110 }
111
112 /*
113 * Converts a value generated by the adapted random number generator
114 * into a value in the input domain for the dependent random number
115 * distribution.
116 *
117 * Because the type traits are compile time constants only the
118 * appropriate clause of the if statements will actually be emitted
119 * by the compiler.
120 */
121 result_type
122 operator()()
123 {
124 result_type __return_value;
125 if (is_integral<_Engine_result_type>::value
126 && is_integral<result_type>::value)
127 __return_value = _M_g();
128 else if (!is_integral<_Engine_result_type>::value
129 && !is_integral<result_type>::value)
130 __return_value = result_type(_M_g() - _M_g.min())
131 / result_type(_M_g.max() - _M_g.min());
132 else if (is_integral<_Engine_result_type>::value
133 && !is_integral<result_type>::value)
134 __return_value = result_type(_M_g() - _M_g.min())
135 / result_type(_M_g.max() - _M_g.min() + result_type(1));
136 else
137 __return_value = (((_M_g() - _M_g.min())
138 / (_M_g.max() - _M_g.min()))
139 * std::numeric_limits<result_type>::max());
140 return __return_value;
141 }
142
143 private:
144 _Engine _M_g;
145 };
146
147 // Specialization for _Engine*.
148 template<typename _Engine, typename _Distribution>
149 struct _Adaptor<_Engine*, _Distribution>
150 {
151 typedef typename _Engine::result_type _Engine_result_type;
152 typedef typename _Distribution::input_type result_type;
153
154 public:
155 _Adaptor(_Engine* __g)
156 : _M_g(__g) { }
157
158 result_type
159 min() const
160 {
161 result_type __return_value;
162 if (is_integral<_Engine_result_type>::value
163 && is_integral<result_type>::value)
164 __return_value = _M_g->min();
165 else
166 __return_value = result_type(0);
167 return __return_value;
168 }
169
170 result_type
171 max() const
172 {
173 result_type __return_value;
174 if (is_integral<_Engine_result_type>::value
175 && is_integral<result_type>::value)
176 __return_value = _M_g->max();
177 else if (!is_integral<result_type>::value)
178 __return_value = result_type(1);
179 else
180 __return_value = std::numeric_limits<result_type>::max() - 1;
181 return __return_value;
182 }
183
184 result_type
185 operator()()
186 {
187 result_type __return_value;
188 if (is_integral<_Engine_result_type>::value
189 && is_integral<result_type>::value)
190 __return_value = (*_M_g)();
191 else if (!is_integral<_Engine_result_type>::value
192 && !is_integral<result_type>::value)
193 __return_value = result_type((*_M_g)() - _M_g->min())
194 / result_type(_M_g->max() - _M_g->min());
195 else if (is_integral<_Engine_result_type>::value
196 && !is_integral<result_type>::value)
197 __return_value = result_type((*_M_g)() - _M_g->min())
198 / result_type(_M_g->max() - _M_g->min() + result_type(1));
199 else
200 __return_value = ((((*_M_g)() - _M_g->min())
201 / (_M_g->max() - _M_g->min()))
202 * std::numeric_limits<result_type>::max());
203 return __return_value;
204 }
205
206 private:
207 _Engine* _M_g;
208 };
209 } // namespace __detail
210
211 /**
212 * Produces random numbers on a given distribution function using a
213 * non-uniform random number generation engine.
214 *
215 * @todo the engine_value_type needs to be studied more carefully.
216 */
217 template<typename _Engine, typename _Dist>
218 class variate_generator
219 {
220 // Concept requirements.
221 __glibcxx_class_requires(_Engine, _CopyConstructibleConcept)
222 // __glibcxx_class_requires(_Engine, _EngineConcept)
223 // __glibcxx_class_requires(_Dist, _EngineConcept)
224
225 public:
226 typedef _Engine engine_type;
227 typedef __detail::_Adaptor<_Engine, _Dist> engine_value_type;
228 typedef _Dist distribution_type;
229 typedef typename _Dist::result_type result_type;
230
231 // tr1:5.1.1 table 5.1 requirement
232 typedef typename __gnu_cxx::__enable_if<
233 is_arithmetic<result_type>::value, result_type>::__type _IsValidType;
234
235 /**
236 * Constructs a variate generator with the uniform random number
237 * generator @p __eng for the random distribution @p __dist.
238 *
239 * @throws Any exceptions which may thrown by the copy constructors of
240 * the @p _Engine or @p _Dist objects.
241 */
242 variate_generator(engine_type __eng, distribution_type __dist)
243 : _M_engine(__eng), _M_dist(__dist) { }
244
245 /**
246 * Gets the next generated value on the distribution.
247 */
248 result_type
249 operator()()
250 { return _M_dist(_M_engine); }
251
252 /**
253 * WTF?
254 */
255 template<typename _Tp>
256 result_type
257 operator()(_Tp __value)
258 { return _M_dist(_M_engine, __value); }
259
260 /**
261 * Gets a reference to the underlying uniform random number generator
262 * object.
263 */
264 engine_value_type&
265 engine()
266 { return _M_engine; }
267
268 /**
269 * Gets a const reference to the underlying uniform random number
270 * generator object.
271 */
272 const engine_value_type&
273 engine() const
274 { return _M_engine; }
275
276 /**
277 * Gets a reference to the underlying random distribution.
278 */
279 distribution_type&
280 distribution()
281 { return _M_dist; }
282
283 /**
284 * Gets a const reference to the underlying random distribution.
285 */
286 const distribution_type&
287 distribution() const
288 { return _M_dist; }
289
290 /**
291 * Gets the closed lower bound of the distribution interval.
292 */
293 result_type
294 min() const
295 { return this->distribution().min(); }
296
297 /**
298 * Gets the closed upper bound of the distribution interval.
299 */
300 result_type
301 max() const
302 { return this->distribution().max(); }
303
304 private:
305 engine_value_type _M_engine;
306 distribution_type _M_dist;
307 };
308
309
310 /**
311 * @defgroup tr1_random_generators Random Number Generators
312 * @ingroup tr1_random
313 *
314 * These classes define objects which provide random or pseudorandom
315 * numbers, either from a discrete or a continuous interval. The
316 * random number generator supplied as a part of this library are
317 * all uniform random number generators which provide a sequence of
318 * random number uniformly distributed over their range.
319 *
320 * A number generator is a function object with an operator() that
321 * takes zero arguments and returns a number.
322 *
323 * A compliant random number generator must satisfy the following
324 * requirements. <table border=1 cellpadding=10 cellspacing=0>
325 * <caption align=top>Random Number Generator Requirements</caption>
326 * <tr><td>To be documented.</td></tr> </table>
327 *
328 * @{
329 */
330
331 /**
332 * @brief A model of a linear congruential random number generator.
333 *
334 * A random number generator that produces pseudorandom numbers using the
335 * linear function @f$x_{i+1}\leftarrow(ax_{i} + c) \bmod m @f$.
336 *
337 * The template parameter @p _UIntType must be an unsigned integral type
338 * large enough to store values up to (__m-1). If the template parameter
339 * @p __m is 0, the modulus @p __m used is
340 * std::numeric_limits<_UIntType>::max() plus 1. Otherwise, the template
341 * parameters @p __a and @p __c must be less than @p __m.
342 *
343 * The size of the state is @f$ 1 @f$.
344 */
345 template<class _UIntType, _UIntType __a, _UIntType __c, _UIntType __m>
346 class linear_congruential
347 {
348 __glibcxx_class_requires(_UIntType, _UnsignedIntegerConcept)
349 // __glibcpp_class_requires(__a < __m && __c < __m)
350
351 public:
352 /** The type of the generated random value. */
353 typedef _UIntType result_type;
354
355 /** The multiplier. */
356 static const _UIntType multiplier = __a;
357 /** An increment. */
358 static const _UIntType increment = __c;
359 /** The modulus. */
360 static const _UIntType modulus = __m;
361
362 /**
363 * Constructs a %linear_congruential random number generator engine with
364 * seed @p __s. The default seed value is 1.
365 *
366 * @param __s The initial seed value.
367 */
368 explicit
369 linear_congruential(unsigned long __x0 = 1)
370 { this->seed(__x0); }
371
372 /**
373 * Constructs a %linear_congruential random number generator engine
374 * seeded from the generator function @p __g.
375 *
376 * @param __g The seed generator function.
377 */
378 template<class _Gen>
379 linear_congruential(_Gen& __g)
380 { this->seed(__g); }
381
382 /**
383 * Reseeds the %linear_congruential random number generator engine
384 * sequence to the seed @g __s.
385 *
386 * @param __s The new seed.
387 */
388 void
389 seed(unsigned long __s = 1);
390
391 /**
392 * Reseeds the %linear_congruential random number generator engine
393 * sequence using values from the generator function @p __g.
394 *
395 * @param __g the seed generator function.
396 */
397 template<class _Gen>
398 void
399 seed(_Gen& __g)
400 { seed(__g, typename is_fundamental<_Gen>::type()); }
401
402 /**
403 * Gets the smallest possible value in the output range.
404 *
405 * The minimum depends on the @p __c parameter: if it is zero, the
406 * minimum generated must be > 0, otherwise 0 is allowed.
407 */
408 result_type
409 min() const
410 { return (__detail::__mod<_UIntType, 1, 0, __m>(__c) == 0) ? 1 : 0; }
411
412 /**
413 * Gets the largest possible value in the output range.
414 */
415 result_type
416 max() const
417 { return __m - 1; }
418
419 /**
420 * Gets the next random number in the sequence.
421 */
422 result_type
423 operator()();
424
425 /**
426 * Compares two linear congruential random number generator
427 * objects of the same type for equality.
428 *
429 * @param __lhs A linear congruential random number generator object.
430 * @param __rhs Another linear congruential random number generator obj.
431 *
432 * @returns true if the two objects are equal, false otherwise.
433 */
434 friend bool
435 operator==(const linear_congruential& __lhs,
436 const linear_congruential& __rhs)
437 { return __lhs._M_x == __rhs._M_x; }
438
439 /**
440 * Compares two linear congruential random number generator
441 * objects of the same type for inequality.
442 *
443 * @param __lhs A linear congruential random number generator object.
444 * @param __rhs Another linear congruential random number generator obj.
445 *
446 * @returns true if the two objects are not equal, false otherwise.
447 */
448 friend bool
449 operator!=(const linear_congruential& __lhs,
450 const linear_congruential& __rhs)
451 { return !(__lhs == __rhs); }
452
453 /**
454 * Writes the textual representation of the state x(i) of x to @p __os.
455 *
456 * @param __os The output stream.
457 * @param __lcr A % linear_congruential random number generator.
458 * @returns __os.
459 */
460 template<class _UIntType1, _UIntType1 __a1, _UIntType1 __c1,
461 _UIntType1 __m1,
462 typename _CharT, typename _Traits>
463 friend std::basic_ostream<_CharT, _Traits>&
464 operator<<(std::basic_ostream<_CharT, _Traits>& __os,
465 const linear_congruential<_UIntType1, __a1, __c1,
466 __m1>& __lcr);
467
468 /**
469 * Sets the state of the engine by reading its textual
470 * representation from @p __is.
471 *
472 * The textual representation must have been previously written using an
473 * output stream whose imbued locale and whose type's template
474 * specialization arguments _CharT and _Traits were the same as those of
475 * @p __is.
476 *
477 * @param __is The input stream.
478 * @param __lcr A % linear_congruential random number generator.
479 * @returns __is.
480 */
481 template<class _UIntType1, _UIntType1 __a1, _UIntType1 __c1,
482 _UIntType1 __m1,
483 typename _CharT, typename _Traits>
484 friend std::basic_istream<_CharT, _Traits>&
485 operator>>(std::basic_istream<_CharT, _Traits>& __is,
486 linear_congruential<_UIntType1, __a1, __c1, __m1>& __lcr);
487
488 private:
489 template<class _Gen>
490 void
491 seed(_Gen& __g, true_type)
492 { return seed(static_cast<unsigned long>(__g)); }
493
494 template<class _Gen>
495 void
496 seed(_Gen& __g, false_type);
497
498 _UIntType _M_x;
499 };
500
501 /**
502 * The classic Minimum Standard rand0 of Lewis, Goodman, and Miller.
503 */
504 typedef linear_congruential<unsigned long, 16807, 0, 2147483647> minstd_rand0;
505
506 /**
507 * An alternative LCR (Lehmer Generator function) .
508 */
509 typedef linear_congruential<unsigned long, 48271, 0, 2147483647> minstd_rand;
510
511
512 /**
513 * A generalized feedback shift register discrete random number generator.
514 *
515 * This algorithm avoids multiplication and division and is designed to be
516 * friendly to a pipelined architecture. If the parameters are chosen
517 * correctly, this generator will produce numbers with a very long period and
518 * fairly good apparent entropy, although still not cryptographically strong.
519 *
520 * The best way to use this generator is with the predefined mt19937 class.
521 *
522 * This algorithm was originally invented by Makoto Matsumoto and
523 * Takuji Nishimura.
524 *
525 * @var word_size The number of bits in each element of the state vector.
526 * @var state_size The degree of recursion.
527 * @var shift_size The period parameter.
528 * @var mask_bits The separation point bit index.
529 * @var parameter_a The last row of the twist matrix.
530 * @var output_u The first right-shift tempering matrix parameter.
531 * @var output_s The first left-shift tempering matrix parameter.
532 * @var output_b The first left-shift tempering matrix mask.
533 * @var output_t The second left-shift tempering matrix parameter.
534 * @var output_c The second left-shift tempering matrix mask.
535 * @var output_l The second right-shift tempering matrix parameter.
536 */
537 template<class _UIntType, int __w, int __n, int __m, int __r,
538 _UIntType __a, int __u, int __s, _UIntType __b, int __t,
539 _UIntType __c, int __l>
540 class mersenne_twister
541 {
542 __glibcxx_class_requires(_UIntType, _UnsignedIntegerConcept)
543
544 public:
545 // types
546 typedef _UIntType result_type;
547
548 // parameter values
549 static const int word_size = __w;
550 static const int state_size = __n;
551 static const int shift_size = __m;
552 static const int mask_bits = __r;
553 static const _UIntType parameter_a = __a;
554 static const int output_u = __u;
555 static const int output_s = __s;
556 static const _UIntType output_b = __b;
557 static const int output_t = __t;
558 static const _UIntType output_c = __c;
559 static const int output_l = __l;
560
561 // constructors and member function
562 mersenne_twister()
563 { seed(); }
564
565 explicit
566 mersenne_twister(unsigned long __value)
567 { seed(__value); }
568
569 template<class _Gen>
570 mersenne_twister(_Gen& __g)
571 { seed(__g); }
572
573 void
574 seed()
575 { seed(5489UL); }
576
577 void
578 seed(unsigned long __value);
579
580 template<class _Gen>
581 void
582 seed(_Gen& __g)
583 { seed(__g, typename is_fundamental<_Gen>::type()); }
584
585 result_type
586 min() const
587 { return 0; };
588
589 result_type
590 max() const
591 { return __detail::_Shift<_UIntType, __w>::__value - 1; }
592
593 result_type
594 operator()();
595
596 /**
597 * Compares two % mersenne_twister random number generator objects of
598 * the same type for equality.
599 *
600 * @param __lhs A % mersenne_twister random number generator object.
601 * @param __rhs Another % mersenne_twister random number generator
602 * object.
603 *
604 * @returns true if the two objects are equal, false otherwise.
605 */
606 friend bool
607 operator==(const mersenne_twister& __lhs,
608 const mersenne_twister& __rhs)
609 { return std::equal(__lhs._M_x, __lhs._M_x + state_size, __rhs._M_x); }
610
611 /**
612 * Compares two % mersenne_twister random number generator objects of
613 * the same type for inequality.
614 *
615 * @param __lhs A % mersenne_twister random number generator object.
616 * @param __rhs Another % mersenne_twister random number generator
617 * object.
618 *
619 * @returns true if the two objects are not equal, false otherwise.
620 */
621 friend bool
622 operator!=(const mersenne_twister& __lhs,
623 const mersenne_twister& __rhs)
624 { return !(__lhs == __rhs); }
625
626 /**
627 * Inserts the current state of a % mersenne_twister random number
628 * generator engine @p __x into the output stream @p __os.
629 *
630 * @param __os An output stream.
631 * @param __x A % mersenne_twister random number generator engine.
632 *
633 * @returns The output stream with the state of @p __x inserted or in
634 * an error state.
635 */
636 template<class _UIntType1, int __w1, int __n1, int __m1, int __r1,
637 _UIntType1 __a1, int __u1, int __s1, _UIntType1 __b1, int __t1,
638 _UIntType1 __c1, int __l1,
639 typename _CharT, typename _Traits>
640 friend std::basic_ostream<_CharT, _Traits>&
641 operator<<(std::basic_ostream<_CharT, _Traits>& __os,
642 const mersenne_twister<_UIntType1, __w1, __n1, __m1, __r1,
643 __a1, __u1, __s1, __b1, __t1, __c1, __l1>& __x);
644
645 /**
646 * Extracts the current state of a % mersenne_twister random number
647 * generator engine @p __x from the input stream @p __is.
648 *
649 * @param __is An input stream.
650 * @param __x A % mersenne_twister random number generator engine.
651 *
652 * @returns The input stream with the state of @p __x extracted or in
653 * an error state.
654 */
655 template<class _UIntType1, int __w1, int __n1, int __m1, int __r1,
656 _UIntType1 __a1, int __u1, int __s1, _UIntType1 __b1, int __t1,
657 _UIntType1 __c1, int __l1,
658 typename _CharT, typename _Traits>
659 friend std::basic_istream<_CharT, _Traits>&
660 operator>>(std::basic_istream<_CharT, _Traits>& __is,
661 mersenne_twister<_UIntType1, __w1, __n1, __m1, __r1,
662 __a1, __u1, __s1, __b1, __t1, __c1, __l1>& __x);
663
664 private:
665 template<class _Gen>
666 void
667 seed(_Gen& __g, true_type)
668 { return seed(static_cast<unsigned long>(__g)); }
669
670 template<class _Gen>
671 void
672 seed(_Gen& __g, false_type);
673
674 _UIntType _M_x[state_size];
675 int _M_p;
676 };
677
678 /**
679 * The classic Mersenne Twister.
680 *
681 * Reference:
682 * M. Matsumoto and T. Nishimura, "Mersenne Twister: A 623-Dimensionally
683 * Equidistributed Uniform Pseudo-Random Number Generator", ACM Transactions
684 * on Modeling and Computer Simulation, Vol. 8, No. 1, January 1998, pp 3-30.
685 */
686 typedef mersenne_twister<
687 unsigned long, 32, 624, 397, 31,
688 0x9908b0dful, 11, 7,
689 0x9d2c5680ul, 15,
690 0xefc60000ul, 18
691 > mt19937;
692
693
694 /**
695 * @brief The Marsaglia-Zaman generator.
696 *
697 * This is a model of a Generalized Fibonacci discrete random number
698 * generator, sometimes referred to as the SWC generator.
699 *
700 * A discrete random number generator that produces pseudorandom
701 * numbers using @f$x_{i}\leftarrow(x_{i - s} - x_{i - r} -
702 * carry_{i-1}) \bmod m @f$.
703 *
704 * The size of the state is @f$ r @f$
705 * and the maximum period of the generator is @f$ m^r - m^s -1 @f$.
706 *
707 * N1688[4.13] says "the template parameter _IntType shall denote an integral
708 * type large enough to store values up to m."
709 *
710 * @var _M_x The state of the generator. This is a ring buffer.
711 * @var _M_carry The carry.
712 * @var _M_p Current index of x(i - r).
713 */
714 template<typename _IntType, _IntType __m, int __s, int __r>
715 class subtract_with_carry
716 {
717 __glibcxx_class_requires(_IntType, _IntegerConcept)
718
719 public:
720 /** The type of the generated random value. */
721 typedef _IntType result_type;
722
723 // parameter values
724 static const _IntType modulus = __m;
725 static const int long_lag = __r;
726 static const int short_lag = __s;
727
728 /**
729 * Constructs a default-initialized % subtract_with_carry random number
730 * generator.
731 */
732 subtract_with_carry()
733 { this->seed(); }
734
735 /**
736 * Constructs an explicitly seeded % subtract_with_carry random number
737 * generator.
738 */
739 explicit
740 subtract_with_carry(unsigned long __value)
741 { this->seed(__value); }
742
743 /**
744 * Constructs a %subtract_with_carry random number generator engine
745 * seeded from the generator function @p __g.
746 *
747 * @param __g The seed generator function.
748 */
749 template<class _Gen>
750 subtract_with_carry(_Gen& __g)
751 { this->seed(__g); }
752
753 /**
754 * Seeds the initial state @f$ x_0 @f$ of the random number generator.
755 *
756 * N1688[4.19] modifies this as follows. If @p __value == 0,
757 * sets value to 19780503. In any case, with a linear
758 * congruential generator lcg(i) having parameters @f$ m_{lcg} =
759 * 2147483563, a_{lcg} = 40014, c_{lcg} = 0, and lcg(0) = value
760 * @f$, sets @f$ x_{-r} \dots x_{-1} @f$ to @f$ lcg(1) \bmod m
761 * \dots lcg(r) \bmod m @f$ respectively. If @f$ x_{-1} = 0 @f$
762 * set carry to 1, otherwise sets carry to 0.
763 */
764 void
765 seed(unsigned long __value = 19780503);
766
767 /**
768 * Seeds the initial state @f$ x_0 @f$ of the % subtract_with_carry
769 * random number generator.
770 */
771 template<class _Gen>
772 void
773 seed(_Gen& __g)
774 { seed(__g, typename is_fundamental<_Gen>::type()); }
775
776 /**
777 * Gets the inclusive minimum value of the range of random integers
778 * returned by this generator.
779 */
780 result_type
781 min() const
782 { return 0; }
783
784 /**
785 * Gets the inclusive maximum value of the range of random integers
786 * returned by this generator.
787 */
788 result_type
789 max() const
790 { return this->modulus - 1; }
791
792 /**
793 * Gets the next random number in the sequence.
794 */
795 result_type
796 operator()();
797
798 /**
799 * Compares two % subtract_with_carry random number generator objects of
800 * the same type for equality.
801 *
802 * @param __lhs A % subtract_with_carry random number generator object.
803 * @param __rhs Another % subtract_with_carry random number generator
804 * object.
805 *
806 * @returns true if the two objects are equal, false otherwise.
807 */
808 friend bool
809 operator==(const subtract_with_carry& __lhs,
810 const subtract_with_carry& __rhs)
811 { return std::equal(__lhs._M_x, __lhs._M_x + long_lag, __rhs._M_x); }
812
813 /**
814 * Compares two % subtract_with_carry random number generator objects of
815 * the same type for inequality.
816 *
817 * @param __lhs A % subtract_with_carry random number generator object.
818 * @param __rhs Another % subtract_with_carry random number generator
819 * object.
820 *
821 * @returns true if the two objects are not equal, false otherwise.
822 */
823 friend bool
824 operator!=(const subtract_with_carry& __lhs,
825 const subtract_with_carry& __rhs)
826 { return !(__lhs == __rhs); }
827
828 /**
829 * Inserts the current state of a % subtract_with_carry random number
830 * generator engine @p __x into the output stream @p __os.
831 *
832 * @param __os An output stream.
833 * @param __x A % subtract_with_carry random number generator engine.
834 *
835 * @returns The output stream with the state of @p __x inserted or in
836 * an error state.
837 */
838 template<typename _IntType1, _IntType1 __m1, int __s1, int __r1,
839 typename _CharT, typename _Traits>
840 friend std::basic_ostream<_CharT, _Traits>&
841 operator<<(std::basic_ostream<_CharT, _Traits>& __os,
842 const subtract_with_carry<_IntType1, __m1, __s1,
843 __r1>& __x);
844
845 /**
846 * Extracts the current state of a % subtract_with_carry random number
847 * generator engine @p __x from the input stream @p __is.
848 *
849 * @param __is An input stream.
850 * @param __x A % subtract_with_carry random number generator engine.
851 *
852 * @returns The input stream with the state of @p __x extracted or in
853 * an error state.
854 */
855 template<typename _IntType1, _IntType1 __m1, int __s1, int __r1,
856 typename _CharT, typename _Traits>
857 friend std::basic_istream<_CharT, _Traits>&
858 operator>>(std::basic_istream<_CharT, _Traits>& __is,
859 subtract_with_carry<_IntType1, __m1, __s1, __r1>& __x);
860
861 private:
862 template<class _Gen>
863 void
864 seed(_Gen& __g, true_type)
865 { return seed(static_cast<unsigned long>(__g)); }
866
867 template<class _Gen>
868 void
869 seed(_Gen& __g, false_type);
870
871 typedef typename __gnu_cxx::__add_unsigned<_IntType>::__type _UIntType;
872
873 _UIntType _M_x[long_lag];
874 _UIntType _M_carry;
875 int _M_p;
876 };
877
878
879 /**
880 * @brief The Marsaglia-Zaman generator (floats version).
881 *
882 * @var _M_x The state of the generator. This is a ring buffer.
883 * @var _M_carry The carry.
884 * @var _M_p Current index of x(i - r).
885 * @var _M_npows Precomputed negative powers of 2.
886 */
887 template<typename _RealType, int __w, int __s, int __r>
888 class subtract_with_carry_01
889 {
890 public:
891 /** The type of the generated random value. */
892 typedef _RealType result_type;
893
894 // parameter values
895 static const int word_size = __w;
896 static const int long_lag = __r;
897 static const int short_lag = __s;
898
899 /**
900 * Constructs a default-initialized % subtract_with_carry_01 random
901 * number generator.
902 */
903 subtract_with_carry_01()
904 {
905 this->seed();
906 _M_initialize_npows();
907 }
908
909 /**
910 * Constructs an explicitly seeded % subtract_with_carry_01 random number
911 * generator.
912 */
913 explicit
914 subtract_with_carry_01(unsigned long __value)
915 {
916 this->seed(__value);
917 _M_initialize_npows();
918 }
919
920 /**
921 * Constructs a % subtract_with_carry_01 random number generator engine
922 * seeded from the generator function @p __g.
923 *
924 * @param __g The seed generator function.
925 */
926 template<class _Gen>
927 subtract_with_carry_01(_Gen& __g)
928 {
929 this->seed(__g);
930 _M_initialize_npows();
931 }
932
933 /**
934 * Seeds the initial state @f$ x_0 @f$ of the random number generator.
935 */
936 void
937 seed(unsigned long __value = 19780503);
938
939 /**
940 * Seeds the initial state @f$ x_0 @f$ of the % subtract_with_carry_01
941 * random number generator.
942 */
943 template<class _Gen>
944 void
945 seed(_Gen& __g)
946 { seed(__g, typename is_fundamental<_Gen>::type()); }
947
948 /**
949 * Gets the minimum value of the range of random floats
950 * returned by this generator.
951 */
952 result_type
953 min() const
954 { return 0.0; }
955
956 /**
957 * Gets the maximum value of the range of random floats
958 * returned by this generator.
959 */
960 result_type
961 max() const
962 { return 1.0; }
963
964 /**
965 * Gets the next random number in the sequence.
966 */
967 result_type
968 operator()();
969
970 /**
971 * Compares two % subtract_with_carry_01 random number generator objects
972 * of the same type for equality.
973 *
974 * @param __lhs A % subtract_with_carry_01 random number
975 * generator object.
976 * @param __rhs Another % subtract_with_carry_01 random number generator
977 * object.
978 *
979 * @returns true if the two objects are equal, false otherwise.
980 */
981 friend bool
982 operator==(const subtract_with_carry_01& __lhs,
983 const subtract_with_carry_01& __rhs)
984 {
985 for (int __i = 0; __i < long_lag; ++__i)
986 if (!std::equal(__lhs._M_x[__i], __lhs._M_x[__i] + __n,
987 __rhs._M_x[__i]))
988 return false;
989 return true;
990 }
991
992 /**
993 * Compares two % subtract_with_carry_01 random number generator objects
994 * of the same type for inequality.
995 *
996 * @param __lhs A % subtract_with_carry_01 random number
997 * generator object.
998 *
999 * @param __rhs Another % subtract_with_carry_01 random number generator
1000 * object.
1001 *
1002 * @returns true if the two objects are not equal, false otherwise.
1003 */
1004 friend bool
1005 operator!=(const subtract_with_carry_01& __lhs,
1006 const subtract_with_carry_01& __rhs)
1007 { return !(__lhs == __rhs); }
1008
1009 /**
1010 * Inserts the current state of a % subtract_with_carry_01 random number
1011 * generator engine @p __x into the output stream @p __os.
1012 *
1013 * @param __os An output stream.
1014 * @param __x A % subtract_with_carry_01 random number generator engine.
1015 *
1016 * @returns The output stream with the state of @p __x inserted or in
1017 * an error state.
1018 */
1019 template<typename _RealType1, int __w1, int __s1, int __r1,
1020 typename _CharT, typename _Traits>
1021 friend std::basic_ostream<_CharT, _Traits>&
1022 operator<<(std::basic_ostream<_CharT, _Traits>& __os,
1023 const subtract_with_carry_01<_RealType1, __w1, __s1,
1024 __r1>& __x);
1025
1026 /**
1027 * Extracts the current state of a % subtract_with_carry_01 random number
1028 * generator engine @p __x from the input stream @p __is.
1029 *
1030 * @param __is An input stream.
1031 * @param __x A % subtract_with_carry_01 random number generator engine.
1032 *
1033 * @returns The input stream with the state of @p __x extracted or in
1034 * an error state.
1035 */
1036 template<typename _RealType1, int __w1, int __s1, int __r1,
1037 typename _CharT, typename _Traits>
1038 friend std::basic_istream<_CharT, _Traits>&
1039 operator>>(std::basic_istream<_CharT, _Traits>& __is,
1040 subtract_with_carry_01<_RealType1, __w1, __s1, __r1>& __x);
1041
1042 private:
1043 template<class _Gen>
1044 void
1045 seed(_Gen& __g, true_type)
1046 { return seed(static_cast<unsigned long>(__g)); }
1047
1048 template<class _Gen>
1049 void
1050 seed(_Gen& __g, false_type);
1051
1052 void
1053 _M_initialize_npows();
1054
1055 static const int __n = (__w + 31) / 32;
1056
1057 typedef __detail::_UInt32Type _UInt32Type;
1058 _UInt32Type _M_x[long_lag][__n];
1059 _RealType _M_npows[__n];
1060 _UInt32Type _M_carry;
1061 int _M_p;
1062 };
1063
1064 typedef subtract_with_carry_01<float, 24, 10, 24> ranlux_base_01;
1065
1066 // _GLIBCXX_RESOLVE_LIB_DEFECTS
1067 // 508. Bad parameters for ranlux64_base_01.
1068 typedef subtract_with_carry_01<double, 48, 5, 12> ranlux64_base_01;
1069
1070
1071 /**
1072 * Produces random numbers from some base engine by discarding blocks of
1073 * data.
1074 *
1075 * 0 <= @p __r <= @p __p
1076 */
1077 template<class _UniformRandomNumberGenerator, int __p, int __r>
1078 class discard_block
1079 {
1080 // __glibcxx_class_requires(typename base_type::result_type,
1081 // ArithmeticTypeConcept)
1082
1083 public:
1084 /** The type of the underlying generator engine. */
1085 typedef _UniformRandomNumberGenerator base_type;
1086 /** The type of the generated random value. */
1087 typedef typename base_type::result_type result_type;
1088
1089 // parameter values
1090 static const int block_size = __p;
1091 static const int used_block = __r;
1092
1093 /**
1094 * Constructs a default %discard_block engine.
1095 *
1096 * The underlying engine is default constructed as well.
1097 */
1098 discard_block()
1099 : _M_n(0) { }
1100
1101 /**
1102 * Copy constructs a %discard_block engine.
1103 *
1104 * Copies an existing base class random number generator.
1105 * @param rng An existing (base class) engine object.
1106 */
1107 explicit
1108 discard_block(const base_type& __rng)
1109 : _M_b(__rng), _M_n(0) { }
1110
1111 /**
1112 * Seed constructs a %discard_block engine.
1113 *
1114 * Constructs the underlying generator engine seeded with @p __s.
1115 * @param __s A seed value for the base class engine.
1116 */
1117 explicit
1118 discard_block(unsigned long __s)
1119 : _M_b(__s), _M_n(0) { }
1120
1121 /**
1122 * Generator construct a %discard_block engine.
1123 *
1124 * @param __g A seed generator function.
1125 */
1126 template<class _Gen>
1127 discard_block(_Gen& __g)
1128 : _M_b(__g), _M_n(0) { }
1129
1130 /**
1131 * Reseeds the %discard_block object with the default seed for the
1132 * underlying base class generator engine.
1133 */
1134 void seed()
1135 {
1136 _M_b.seed();
1137 _M_n = 0;
1138 }
1139
1140 /**
1141 * Reseeds the %discard_block object with the given seed generator
1142 * function.
1143 * @param __g A seed generator function.
1144 */
1145 template<class _Gen>
1146 void seed(_Gen& __g)
1147 {
1148 _M_b.seed(__g);
1149 _M_n = 0;
1150 }
1151
1152 /**
1153 * Gets a const reference to the underlying generator engine object.
1154 */
1155 const base_type&
1156 base() const
1157 { return _M_b; }
1158
1159 /**
1160 * Gets the minimum value in the generated random number range.
1161 */
1162 result_type
1163 min() const
1164 { return _M_b.min(); }
1165
1166 /**
1167 * Gets the maximum value in the generated random number range.
1168 */
1169 result_type
1170 max() const
1171 { return _M_b.max(); }
1172
1173 /**
1174 * Gets the next value in the generated random number sequence.
1175 */
1176 result_type
1177 operator()();
1178
1179 /**
1180 * Compares two %discard_block random number generator objects of
1181 * the same type for equality.
1182 *
1183 * @param __lhs A %discard_block random number generator object.
1184 * @param __rhs Another %discard_block random number generator
1185 * object.
1186 *
1187 * @returns true if the two objects are equal, false otherwise.
1188 */
1189 friend bool
1190 operator==(const discard_block& __lhs, const discard_block& __rhs)
1191 { return (__lhs._M_b == __rhs._M_b) && (__lhs._M_n == __rhs._M_n); }
1192
1193 /**
1194 * Compares two %discard_block random number generator objects of
1195 * the same type for inequality.
1196 *
1197 * @param __lhs A %discard_block random number generator object.
1198 * @param __rhs Another %discard_block random number generator
1199 * object.
1200 *
1201 * @returns true if the two objects are not equal, false otherwise.
1202 */
1203 friend bool
1204 operator!=(const discard_block& __lhs, const discard_block& __rhs)
1205 { return !(__lhs == __rhs); }
1206
1207 /**
1208 * Inserts the current state of a %discard_block random number
1209 * generator engine @p __x into the output stream @p __os.
1210 *
1211 * @param __os An output stream.
1212 * @param __x A %discard_block random number generator engine.
1213 *
1214 * @returns The output stream with the state of @p __x inserted or in
1215 * an error state.
1216 */
1217 template<class _UniformRandomNumberGenerator1, int __p1, int __r1,
1218 typename _CharT, typename _Traits>
1219 friend std::basic_ostream<_CharT, _Traits>&
1220 operator<<(std::basic_ostream<_CharT, _Traits>& __os,
1221 const discard_block<_UniformRandomNumberGenerator1,
1222 __p1, __r1>& __x);
1223
1224 /**
1225 * Extracts the current state of a % subtract_with_carry random number
1226 * generator engine @p __x from the input stream @p __is.
1227 *
1228 * @param __is An input stream.
1229 * @param __x A %discard_block random number generator engine.
1230 *
1231 * @returns The input stream with the state of @p __x extracted or in
1232 * an error state.
1233 */
1234 template<class _UniformRandomNumberGenerator1, int __p1, int __r1,
1235 typename _CharT, typename _Traits>
1236 friend std::basic_istream<_CharT, _Traits>&
1237 operator>>(std::basic_istream<_CharT, _Traits>& __is,
1238 discard_block<_UniformRandomNumberGenerator1,
1239 __p1, __r1>& __x);
1240
1241 private:
1242 base_type _M_b;
1243 int _M_n;
1244 };
1245
1246
1247 /**
1248 * James's luxury-level-3 integer adaptation of Luescher's generator.
1249 */
1250 typedef discard_block<
1251 subtract_with_carry<unsigned long, (1UL << 24), 10, 24>,
1252 223,
1253 24
1254 > ranlux3;
1255
1256 /**
1257 * James's luxury-level-4 integer adaptation of Luescher's generator.
1258 */
1259 typedef discard_block<
1260 subtract_with_carry<unsigned long, (1UL << 24), 10, 24>,
1261 389,
1262 24
1263 > ranlux4;
1264
1265 typedef discard_block<
1266 subtract_with_carry_01<float, 24, 10, 24>,
1267 223,
1268 24
1269 > ranlux3_01;
1270
1271 typedef discard_block<
1272 subtract_with_carry_01<float, 24, 10, 24>,
1273 389,
1274 24
1275 > ranlux4_01;
1276
1277
1278 /**
1279 * A random number generator adaptor class that combines two random number
1280 * generator engines into a single output sequence.
1281 */
1282 template<class _UniformRandomNumberGenerator1, int __s1,
1283 class _UniformRandomNumberGenerator2, int __s2>
1284 class xor_combine
1285 {
1286 // __glibcxx_class_requires(typename _UniformRandomNumberGenerator1::
1287 // result_type, ArithmeticTypeConcept)
1288 // __glibcxx_class_requires(typename _UniformRandomNumberGenerator2::
1289 // result_type, ArithmeticTypeConcept)
1290
1291 public:
1292 /** The type of the first underlying generator engine. */
1293 typedef _UniformRandomNumberGenerator1 base1_type;
1294 /** The type of the second underlying generator engine. */
1295 typedef _UniformRandomNumberGenerator2 base2_type;
1296
1297 private:
1298 typedef typename base1_type::result_type _Result_type1;
1299 typedef typename base2_type::result_type _Result_type2;
1300
1301 public:
1302 /** The type of the generated random value. */
1303 typedef typename __gnu_cxx::__conditional_type<(sizeof(_Result_type1)
1304 > sizeof(_Result_type2)),
1305 _Result_type1, _Result_type2>::__type result_type;
1306
1307 // parameter values
1308 static const int shift1 = __s1;
1309 static const int shift2 = __s2;
1310
1311 // constructors and member function
1312 xor_combine()
1313 : _M_b1(), _M_b2()
1314 { _M_initialize_max(); }
1315
1316 xor_combine(const base1_type& __rng1, const base2_type& __rng2)
1317 : _M_b1(__rng1), _M_b2(__rng2)
1318 { _M_initialize_max(); }
1319
1320 xor_combine(unsigned long __s)
1321 : _M_b1(__s), _M_b2(__s + 1)
1322 { _M_initialize_max(); }
1323
1324 template<class _Gen>
1325 xor_combine(_Gen& __g)
1326 : _M_b1(__g), _M_b2(__g)
1327 { _M_initialize_max(); }
1328
1329 void
1330 seed()
1331 {
1332 _M_b1.seed();
1333 _M_b2.seed();
1334 }
1335
1336 template<class _Gen>
1337 void
1338 seed(_Gen& __g)
1339 {
1340 _M_b1.seed(__g);
1341 _M_b2.seed(__g);
1342 }
1343
1344 const base1_type&
1345 base1() const
1346 { return _M_b1; }
1347
1348 const base2_type&
1349 base2() const
1350 { return _M_b2; }
1351
1352 result_type
1353 min() const
1354 { return 0; }
1355
1356 result_type
1357 max() const
1358 { return _M_max; }
1359
1360 /**
1361 * Gets the next random number in the sequence.
1362 */
1363 // NB: Not exactly the TR1 formula, per N2079 instead.
1364 result_type
1365 operator()()
1366 {
1367 return ((result_type(_M_b1() - _M_b1.min()) << shift1)
1368 ^ (result_type(_M_b2() - _M_b2.min()) << shift2));
1369 }
1370
1371 /**
1372 * Compares two %xor_combine random number generator objects of
1373 * the same type for equality.
1374 *
1375 * @param __lhs A %xor_combine random number generator object.
1376 * @param __rhs Another %xor_combine random number generator
1377 * object.
1378 *
1379 * @returns true if the two objects are equal, false otherwise.
1380 */
1381 friend bool
1382 operator==(const xor_combine& __lhs, const xor_combine& __rhs)
1383 {
1384 return (__lhs.base1() == __rhs.base1())
1385 && (__lhs.base2() == __rhs.base2());
1386 }
1387
1388 /**
1389 * Compares two %xor_combine random number generator objects of
1390 * the same type for inequality.
1391 *
1392 * @param __lhs A %xor_combine random number generator object.
1393 * @param __rhs Another %xor_combine random number generator
1394 * object.
1395 *
1396 * @returns true if the two objects are not equal, false otherwise.
1397 */
1398 friend bool
1399 operator!=(const xor_combine& __lhs, const xor_combine& __rhs)
1400 { return !(__lhs == __rhs); }
1401
1402 /**
1403 * Inserts the current state of a %xor_combine random number
1404 * generator engine @p __x into the output stream @p __os.
1405 *
1406 * @param __os An output stream.
1407 * @param __x A %xor_combine random number generator engine.
1408 *
1409 * @returns The output stream with the state of @p __x inserted or in
1410 * an error state.
1411 */
1412 template<class _UniformRandomNumberGenerator11, int __s11,
1413 class _UniformRandomNumberGenerator21, int __s21,
1414 typename _CharT, typename _Traits>
1415 friend std::basic_ostream<_CharT, _Traits>&
1416 operator<<(std::basic_ostream<_CharT, _Traits>& __os,
1417 const xor_combine<_UniformRandomNumberGenerator11, __s11,
1418 _UniformRandomNumberGenerator21, __s21>& __x);
1419
1420 /**
1421 * Extracts the current state of a %xor_combine random number
1422 * generator engine @p __x from the input stream @p __is.
1423 *
1424 * @param __is An input stream.
1425 * @param __x A %xor_combine random number generator engine.
1426 *
1427 * @returns The input stream with the state of @p __x extracted or in
1428 * an error state.
1429 */
1430 template<class _UniformRandomNumberGenerator11, int __s11,
1431 class _UniformRandomNumberGenerator21, int __s21,
1432 typename _CharT, typename _Traits>
1433 friend std::basic_istream<_CharT, _Traits>&
1434 operator>>(std::basic_istream<_CharT, _Traits>& __is,
1435 xor_combine<_UniformRandomNumberGenerator11, __s11,
1436 _UniformRandomNumberGenerator21, __s21>& __x);
1437
1438 private:
1439 void
1440 _M_initialize_max();
1441
1442 result_type
1443 _M_initialize_max_aux(result_type, result_type, int);
1444
1445 base1_type _M_b1;
1446 base2_type _M_b2;
1447 result_type _M_max;
1448 };
1449
1450
1451 /**
1452 * A standard interface to a platform-specific non-deterministic
1453 * random number generator (if any are available).
1454 */
1455 class random_device
1456 {
1457 public:
1458 // types
1459 typedef unsigned int result_type;
1460
1461 // constructors, destructors and member functions
1462
1463 #ifdef _GLIBCXX_USE_RANDOM_TR1
1464
1465 explicit
1466 random_device(const std::string& __token = "/dev/urandom")
1467 {
1468 if ((__token != "/dev/urandom" && __token != "/dev/random")
1469 || !(_M_file = std::fopen(__token.c_str(), "rb")))
1470 std::__throw_runtime_error(__N("random_device::"
1471 "random_device(const std::string&)"));
1472 }
1473
1474 ~random_device()
1475 { std::fclose(_M_file); }
1476
1477 #else
1478
1479 explicit
1480 random_device(const std::string& __token = "mt19937")
1481 : _M_mt(_M_strtoul(__token)) { }
1482
1483 private:
1484 static unsigned long
1485 _M_strtoul(const std::string& __str)
1486 {
1487 unsigned long __ret = 5489UL;
1488 if (__str != "mt19937")
1489 {
1490 const char* __nptr = __str.c_str();
1491 char* __endptr;
1492 __ret = std::strtoul(__nptr, &__endptr, 0);
1493 if (*__nptr == '\0' || *__endptr != '\0')
1494 std::__throw_runtime_error(__N("random_device::_M_strtoul"
1495 "(const std::string&)"));
1496 }
1497 return __ret;
1498 }
1499
1500 public:
1501
1502 #endif
1503
1504 result_type
1505 min() const
1506 { return std::numeric_limits<result_type>::min(); }
1507
1508 result_type
1509 max() const
1510 { return std::numeric_limits<result_type>::max(); }
1511
1512 double
1513 entropy() const
1514 { return 0.0; }
1515
1516 result_type
1517 operator()()
1518 {
1519 #ifdef _GLIBCXX_USE_RANDOM_TR1
1520 result_type __ret;
1521 std::fread(reinterpret_cast<void*>(&__ret), sizeof(result_type),
1522 1, _M_file);
1523 return __ret;
1524 #else
1525 return _M_mt();
1526 #endif
1527 }
1528
1529 private:
1530 random_device(const random_device&);
1531 void operator=(const random_device&);
1532
1533 #ifdef _GLIBCXX_USE_RANDOM_TR1
1534 FILE* _M_file;
1535 #else
1536 mt19937 _M_mt;
1537 #endif
1538 };
1539
1540 /* @} */ // group tr1_random_generators
1541
1542 /**
1543 * @defgroup tr1_random_distributions Random Number Distributions
1544 * @ingroup tr1_random
1545 * @{
1546 */
1547
1548 /**
1549 * @defgroup tr1_random_distributions_discrete Discrete Distributions
1550 * @ingroup tr1_random_distributions
1551 * @{
1552 */
1553
1554 /**
1555 * @brief Uniform discrete distribution for random numbers.
1556 * A discrete random distribution on the range @f$[min, max]@f$ with equal
1557 * probability throughout the range.
1558 */
1559 template<typename _IntType = int>
1560 class uniform_int
1561 {
1562 __glibcxx_class_requires(_IntType, _IntegerConcept)
1563
1564 public:
1565 /** The type of the parameters of the distribution. */
1566 typedef _IntType input_type;
1567 /** The type of the range of the distribution. */
1568 typedef _IntType result_type;
1569
1570 public:
1571 /**
1572 * Constructs a uniform distribution object.
1573 */
1574 explicit
1575 uniform_int(_IntType __min = 0, _IntType __max = 9)
1576 : _M_min(__min), _M_max(__max)
1577 {
1578 _GLIBCXX_DEBUG_ASSERT(_M_min <= _M_max);
1579 }
1580
1581 /**
1582 * Gets the inclusive lower bound of the distribution range.
1583 */
1584 result_type
1585 min() const
1586 { return _M_min; }
1587
1588 /**
1589 * Gets the inclusive upper bound of the distribution range.
1590 */
1591 result_type
1592 max() const
1593 { return _M_max; }
1594
1595 /**
1596 * Resets the distribution state.
1597 *
1598 * Does nothing for the uniform integer distribution.
1599 */
1600 void
1601 reset() { }
1602
1603 /**
1604 * Gets a uniformly distributed random number in the range
1605 * @f$(min, max)@f$.
1606 */
1607 template<typename _UniformRandomNumberGenerator>
1608 result_type
1609 operator()(_UniformRandomNumberGenerator& __urng)
1610 {
1611 typedef typename _UniformRandomNumberGenerator::result_type
1612 _UResult_type;
1613 return _M_call(__urng, _M_min, _M_max,
1614 typename is_integral<_UResult_type>::type());
1615 }
1616
1617 /**
1618 * Gets a uniform random number in the range @f$[0, n)@f$.
1619 *
1620 * This function is aimed at use with std::random_shuffle.
1621 */
1622 template<typename _UniformRandomNumberGenerator>
1623 result_type
1624 operator()(_UniformRandomNumberGenerator& __urng, result_type __n)
1625 {
1626 typedef typename _UniformRandomNumberGenerator::result_type
1627 _UResult_type;
1628 return _M_call(__urng, 0, __n - 1,
1629 typename is_integral<_UResult_type>::type());
1630 }
1631
1632 /**
1633 * Inserts a %uniform_int random number distribution @p __x into the
1634 * output stream @p os.
1635 *
1636 * @param __os An output stream.
1637 * @param __x A %uniform_int random number distribution.
1638 *
1639 * @returns The output stream with the state of @p __x inserted or in
1640 * an error state.
1641 */
1642 template<typename _IntType1, typename _CharT, typename _Traits>
1643 friend std::basic_ostream<_CharT, _Traits>&
1644 operator<<(std::basic_ostream<_CharT, _Traits>& __os,
1645 const uniform_int<_IntType1>& __x);
1646
1647 /**
1648 * Extracts a %uniform_int random number distribution
1649 * @p __x from the input stream @p __is.
1650 *
1651 * @param __is An input stream.
1652 * @param __x A %uniform_int random number generator engine.
1653 *
1654 * @returns The input stream with @p __x extracted or in an error state.
1655 */
1656 template<typename _IntType1, typename _CharT, typename _Traits>
1657 friend std::basic_istream<_CharT, _Traits>&
1658 operator>>(std::basic_istream<_CharT, _Traits>& __is,
1659 uniform_int<_IntType1>& __x);
1660
1661 private:
1662 template<typename _UniformRandomNumberGenerator>
1663 result_type
1664 _M_call(_UniformRandomNumberGenerator& __urng,
1665 result_type __min, result_type __max, true_type);
1666
1667 template<typename _UniformRandomNumberGenerator>
1668 result_type
1669 _M_call(_UniformRandomNumberGenerator& __urng,
1670 result_type __min, result_type __max, false_type)
1671 {
1672 return result_type((__urng() - __urng.min())
1673 / (__urng.max() - __urng.min())
1674 * (__max - __min + 1)) + __min;
1675 }
1676
1677 _IntType _M_min;
1678 _IntType _M_max;
1679 };
1680
1681
1682 /**
1683 * @brief A Bernoulli random number distribution.
1684 *
1685 * Generates a sequence of true and false values with likelihood @f$ p @f$
1686 * that true will come up and @f$ (1 - p) @f$ that false will appear.
1687 */
1688 class bernoulli_distribution
1689 {
1690 public:
1691 typedef int input_type;
1692 typedef bool result_type;
1693
1694 public:
1695 /**
1696 * Constructs a Bernoulli distribution with likelihood @p p.
1697 *
1698 * @param __p [IN] The likelihood of a true result being returned. Must
1699 * be in the interval @f$ [0, 1] @f$.
1700 */
1701 explicit
1702 bernoulli_distribution(double __p = 0.5)
1703 : _M_p(__p)
1704 {
1705 _GLIBCXX_DEBUG_ASSERT((_M_p >= 0.0) && (_M_p <= 1.0));
1706 }
1707
1708 /**
1709 * Gets the @p p parameter of the distribution.
1710 */
1711 double
1712 p() const
1713 { return _M_p; }
1714
1715 /**
1716 * Resets the distribution state.
1717 *
1718 * Does nothing for a Bernoulli distribution.
1719 */
1720 void
1721 reset() { }
1722
1723 /**
1724 * Gets the next value in the Bernoullian sequence.
1725 */
1726 template<class _UniformRandomNumberGenerator>
1727 result_type
1728 operator()(_UniformRandomNumberGenerator& __urng)
1729 {
1730 if ((__urng() - __urng.min()) < _M_p * (__urng.max() - __urng.min()))
1731 return true;
1732 return false;
1733 }
1734
1735 /**
1736 * Inserts a %bernoulli_distribution random number distribution
1737 * @p __x into the output stream @p __os.
1738 *
1739 * @param __os An output stream.
1740 * @param __x A %bernoulli_distribution random number distribution.
1741 *
1742 * @returns The output stream with the state of @p __x inserted or in
1743 * an error state.
1744 */
1745 template<typename _CharT, typename _Traits>
1746 friend std::basic_ostream<_CharT, _Traits>&
1747 operator<<(std::basic_ostream<_CharT, _Traits>& __os,
1748 const bernoulli_distribution& __x);
1749
1750 /**
1751 * Extracts a %bernoulli_distribution random number distribution
1752 * @p __x from the input stream @p __is.
1753 *
1754 * @param __is An input stream.
1755 * @param __x A %bernoulli_distribution random number generator engine.
1756 *
1757 * @returns The input stream with @p __x extracted or in an error state.
1758 */
1759 template<typename _CharT, typename _Traits>
1760 friend std::basic_istream<_CharT, _Traits>&
1761 operator>>(std::basic_istream<_CharT, _Traits>& __is,
1762 bernoulli_distribution& __x)
1763 { return __is >> __x._M_p; }
1764
1765 private:
1766 double _M_p;
1767 };
1768
1769
1770 /**
1771 * @brief A discrete geometric random number distribution.
1772 *
1773 * The formula for the geometric probability mass function is
1774 * @f$ p(i) = (1 - p)p^{i-1} @f$ where @f$ p @f$ is the parameter of the
1775 * distribution.
1776 */
1777 template<typename _IntType = int, typename _RealType = double>
1778 class geometric_distribution
1779 {
1780 public:
1781 // types
1782 typedef _RealType input_type;
1783 typedef _IntType result_type;
1784
1785 // constructors and member function
1786 explicit
1787 geometric_distribution(const _RealType& __p = _RealType(0.5))
1788 : _M_p(__p)
1789 {
1790 _GLIBCXX_DEBUG_ASSERT((_M_p > 0.0) && (_M_p < 1.0));
1791 _M_initialize();
1792 }
1793
1794 /**
1795 * Gets the distribution parameter @p p.
1796 */
1797 _RealType
1798 p() const
1799 { return _M_p; }
1800
1801 void
1802 reset() { }
1803
1804 template<class _UniformRandomNumberGenerator>
1805 result_type
1806 operator()(_UniformRandomNumberGenerator& __urng);
1807
1808 /**
1809 * Inserts a %geometric_distribution random number distribution
1810 * @p __x into the output stream @p __os.
1811 *
1812 * @param __os An output stream.
1813 * @param __x A %geometric_distribution random number distribution.
1814 *
1815 * @returns The output stream with the state of @p __x inserted or in
1816 * an error state.
1817 */
1818 template<typename _IntType1, typename _RealType1,
1819 typename _CharT, typename _Traits>
1820 friend std::basic_ostream<_CharT, _Traits>&
1821 operator<<(std::basic_ostream<_CharT, _Traits>& __os,
1822 const geometric_distribution<_IntType1, _RealType1>& __x);
1823
1824 /**
1825 * Extracts a %geometric_distribution random number distribution
1826 * @p __x from the input stream @p __is.
1827 *
1828 * @param __is An input stream.
1829 * @param __x A %geometric_distribution random number generator engine.
1830 *
1831 * @returns The input stream with @p __x extracted or in an error state.
1832 */
1833 template<typename _CharT, typename _Traits>
1834 friend std::basic_istream<_CharT, _Traits>&
1835 operator>>(std::basic_istream<_CharT, _Traits>& __is,
1836 geometric_distribution& __x)
1837 {
1838 __is >> __x._M_p;
1839 __x._M_initialize();
1840 return __is;
1841 }
1842
1843 private:
1844 void
1845 _M_initialize()
1846 { _M_log_p = std::log(_M_p); }
1847
1848 _RealType _M_p;
1849 _RealType _M_log_p;
1850 };
1851
1852
1853 template<typename _RealType>
1854 class normal_distribution;
1855
1856 /**
1857 * @brief A discrete Poisson random number distribution.
1858 *
1859 * The formula for the Poisson probability mass function is
1860 * @f$ p(i) = \frac{mean^i}{i!} e^{-mean} @f$ where @f$ mean @f$ is the
1861 * parameter of the distribution.
1862 */
1863 template<typename _IntType = int, typename _RealType = double>
1864 class poisson_distribution
1865 {
1866 public:
1867 // types
1868 typedef _RealType input_type;
1869 typedef _IntType result_type;
1870
1871 // constructors and member function
1872 explicit
1873 poisson_distribution(const _RealType& __mean = _RealType(1))
1874 : _M_mean(__mean), _M_nd()
1875 {
1876 _GLIBCXX_DEBUG_ASSERT(_M_mean > 0.0);
1877 _M_initialize();
1878 }
1879
1880 /**
1881 * Gets the distribution parameter @p mean.
1882 */
1883 _RealType
1884 mean() const
1885 { return _M_mean; }
1886
1887 void
1888 reset()
1889 { _M_nd.reset(); }
1890
1891 template<class _UniformRandomNumberGenerator>
1892 result_type
1893 operator()(_UniformRandomNumberGenerator& __urng);
1894
1895 /**
1896 * Inserts a %poisson_distribution random number distribution
1897 * @p __x into the output stream @p __os.
1898 *
1899 * @param __os An output stream.
1900 * @param __x A %poisson_distribution random number distribution.
1901 *
1902 * @returns The output stream with the state of @p __x inserted or in
1903 * an error state.
1904 */
1905 template<typename _IntType1, typename _RealType1,
1906 typename _CharT, typename _Traits>
1907 friend std::basic_ostream<_CharT, _Traits>&
1908 operator<<(std::basic_ostream<_CharT, _Traits>& __os,
1909 const poisson_distribution<_IntType1, _RealType1>& __x);
1910
1911 /**
1912 * Extracts a %poisson_distribution random number distribution
1913 * @p __x from the input stream @p __is.
1914 *
1915 * @param __is An input stream.
1916 * @param __x A %poisson_distribution random number generator engine.
1917 *
1918 * @returns The input stream with @p __x extracted or in an error state.
1919 */
1920 template<typename _IntType1, typename _RealType1,
1921 typename _CharT, typename _Traits>
1922 friend std::basic_istream<_CharT, _Traits>&
1923 operator>>(std::basic_istream<_CharT, _Traits>& __is,
1924 poisson_distribution<_IntType1, _RealType1>& __x);
1925
1926 private:
1927 void
1928 _M_initialize();
1929
1930 // NB: Unused when _GLIBCXX_USE_C99_MATH_TR1 is undefined.
1931 normal_distribution<_RealType> _M_nd;
1932
1933 _RealType _M_mean;
1934
1935 // Hosts either log(mean) or the threshold of the simple method.
1936 _RealType _M_lm_thr;
1937 #if _GLIBCXX_USE_C99_MATH_TR1
1938 _RealType _M_lfm, _M_sm, _M_d, _M_scx, _M_1cx, _M_c2b, _M_cb;
1939 #endif
1940 };
1941
1942
1943 /**
1944 * @brief A discrete binomial random number distribution.
1945 *
1946 * The formula for the binomial probability mass function is
1947 * @f$ p(i) = \binom{n}{i} p^i (1 - p)^{t - i} @f$ where @f$ t @f$
1948 * and @f$ p @f$ are the parameters of the distribution.
1949 */
1950 template<typename _IntType = int, typename _RealType = double>
1951 class binomial_distribution
1952 {
1953 public:
1954 // types
1955 typedef _RealType input_type;
1956 typedef _IntType result_type;
1957
1958 // constructors and member function
1959 explicit
1960 binomial_distribution(_IntType __t = 1,
1961 const _RealType& __p = _RealType(0.5))
1962 : _M_t(__t), _M_p(__p), _M_nd()
1963 {
1964 _GLIBCXX_DEBUG_ASSERT((_M_t >= 0) && (_M_p >= 0.0) && (_M_p <= 1.0));
1965 _M_initialize();
1966 }
1967
1968 /**
1969 * Gets the distribution @p t parameter.
1970 */
1971 _IntType
1972 t() const
1973 { return _M_t; }
1974
1975 /**
1976 * Gets the distribution @p p parameter.
1977 */
1978 _RealType
1979 p() const
1980 { return _M_p; }
1981
1982 void
1983 reset()
1984 { _M_nd.reset(); }
1985
1986 template<class _UniformRandomNumberGenerator>
1987 result_type
1988 operator()(_UniformRandomNumberGenerator& __urng);
1989
1990 /**
1991 * Inserts a %binomial_distribution random number distribution
1992 * @p __x into the output stream @p __os.
1993 *
1994 * @param __os An output stream.
1995 * @param __x A %binomial_distribution random number distribution.
1996 *
1997 * @returns The output stream with the state of @p __x inserted or in
1998 * an error state.
1999 */
2000 template<typename _IntType1, typename _RealType1,
2001 typename _CharT, typename _Traits>
2002 friend std::basic_ostream<_CharT, _Traits>&
2003 operator<<(std::basic_ostream<_CharT, _Traits>& __os,
2004 const binomial_distribution<_IntType1, _RealType1>& __x);
2005
2006 /**
2007 * Extracts a %binomial_distribution random number distribution
2008 * @p __x from the input stream @p __is.
2009 *
2010 * @param __is An input stream.
2011 * @param __x A %binomial_distribution random number generator engine.
2012 *
2013 * @returns The input stream with @p __x extracted or in an error state.
2014 */
2015 template<typename _IntType1, typename _RealType1,
2016 typename _CharT, typename _Traits>
2017 friend std::basic_istream<_CharT, _Traits>&
2018 operator>>(std::basic_istream<_CharT, _Traits>& __is,
2019 binomial_distribution<_IntType1, _RealType1>& __x);
2020
2021 private:
2022 void
2023 _M_initialize();
2024
2025 template<class _UniformRandomNumberGenerator>
2026 result_type
2027 _M_waiting(_UniformRandomNumberGenerator& __urng, _IntType __t);
2028
2029 // NB: Unused when _GLIBCXX_USE_C99_MATH_TR1 is undefined.
2030 normal_distribution<_RealType> _M_nd;
2031
2032 _RealType _M_q;
2033 #if _GLIBCXX_USE_C99_MATH_TR1
2034 _RealType _M_d1, _M_d2, _M_s1, _M_s2, _M_c,
2035 _M_a1, _M_a123, _M_s, _M_lf, _M_lp1p;
2036 #endif
2037 _RealType _M_p;
2038 _IntType _M_t;
2039
2040 bool _M_easy;
2041 };
2042
2043 /* @} */ // group tr1_random_distributions_discrete
2044
2045 /**
2046 * @defgroup tr1_random_distributions_continuous Continuous Distributions
2047 * @ingroup tr1_random_distributions
2048 * @{
2049 */
2050
2051 /**
2052 * @brief Uniform continuous distribution for random numbers.
2053 *
2054 * A continuous random distribution on the range [min, max) with equal
2055 * probability throughout the range. The URNG should be real-valued and
2056 * deliver number in the range [0, 1).
2057 */
2058 template<typename _RealType = double>
2059 class uniform_real
2060 {
2061 public:
2062 // types
2063 typedef _RealType input_type;
2064 typedef _RealType result_type;
2065
2066 public:
2067 /**
2068 * Constructs a uniform_real object.
2069 *
2070 * @param __min [IN] The lower bound of the distribution.
2071 * @param __max [IN] The upper bound of the distribution.
2072 */
2073 explicit
2074 uniform_real(_RealType __min = _RealType(0),
2075 _RealType __max = _RealType(1))
2076 : _M_min(__min), _M_max(__max)
2077 {
2078 _GLIBCXX_DEBUG_ASSERT(_M_min <= _M_max);
2079 }
2080
2081 result_type
2082 min() const
2083 { return _M_min; }
2084
2085 result_type
2086 max() const
2087 { return _M_max; }
2088
2089 void
2090 reset() { }
2091
2092 template<class _UniformRandomNumberGenerator>
2093 result_type
2094 operator()(_UniformRandomNumberGenerator& __urng)
2095 { return (__urng() * (_M_max - _M_min)) + _M_min; }
2096
2097 /**
2098 * Inserts a %uniform_real random number distribution @p __x into the
2099 * output stream @p __os.
2100 *
2101 * @param __os An output stream.
2102 * @param __x A %uniform_real random number distribution.
2103 *
2104 * @returns The output stream with the state of @p __x inserted or in
2105 * an error state.
2106 */
2107 template<typename _RealType1, typename _CharT, typename _Traits>
2108 friend std::basic_ostream<_CharT, _Traits>&
2109 operator<<(std::basic_ostream<_CharT, _Traits>& __os,
2110 const uniform_real<_RealType1>& __x);
2111
2112 /**
2113 * Extracts a %uniform_real random number distribution
2114 * @p __x from the input stream @p __is.
2115 *
2116 * @param __is An input stream.
2117 * @param __x A %uniform_real random number generator engine.
2118 *
2119 * @returns The input stream with @p __x extracted or in an error state.
2120 */
2121 template<typename _RealType1, typename _CharT, typename _Traits>
2122 friend std::basic_istream<_CharT, _Traits>&
2123 operator>>(std::basic_istream<_CharT, _Traits>& __is,
2124 uniform_real<_RealType1>& __x);
2125
2126 private:
2127 _RealType _M_min;
2128 _RealType _M_max;
2129 };
2130
2131
2132 /**
2133 * @brief An exponential continuous distribution for random numbers.
2134 *
2135 * The formula for the exponential probability mass function is
2136 * @f$ p(x) = \lambda e^{-\lambda x} @f$.
2137 *
2138 * <table border=1 cellpadding=10 cellspacing=0>
2139 * <caption align=top>Distribution Statistics</caption>
2140 * <tr><td>Mean</td><td>@f$ \frac{1}{\lambda} @f$</td></tr>
2141 * <tr><td>Median</td><td>@f$ \frac{\ln 2}{\lambda} @f$</td></tr>
2142 * <tr><td>Mode</td><td>@f$ zero @f$</td></tr>
2143 * <tr><td>Range</td><td>@f$[0, \infty]@f$</td></tr>
2144 * <tr><td>Standard Deviation</td><td>@f$ \frac{1}{\lambda} @f$</td></tr>
2145 * </table>
2146 */
2147 template<typename _RealType = double>
2148 class exponential_distribution
2149 {
2150 public:
2151 // types
2152 typedef _RealType input_type;
2153 typedef _RealType result_type;
2154
2155 public:
2156 /**
2157 * Constructs an exponential distribution with inverse scale parameter
2158 * @f$ \lambda @f$.
2159 */
2160 explicit
2161 exponential_distribution(const result_type& __lambda = result_type(1))
2162 : _M_lambda(__lambda)
2163 {
2164 _GLIBCXX_DEBUG_ASSERT(_M_lambda > 0);
2165 }
2166
2167 /**
2168 * Gets the inverse scale parameter of the distribution.
2169 */
2170 _RealType
2171 lambda() const
2172 { return _M_lambda; }
2173
2174 /**
2175 * Resets the distribution.
2176 *
2177 * Has no effect on exponential distributions.
2178 */
2179 void
2180 reset() { }
2181
2182 template<class _UniformRandomNumberGenerator>
2183 result_type
2184 operator()(_UniformRandomNumberGenerator& __urng)
2185 { return -std::log(__urng()) / _M_lambda; }
2186
2187 /**
2188 * Inserts a %exponential_distribution random number distribution
2189 * @p __x into the output stream @p __os.
2190 *
2191 * @param __os An output stream.
2192 * @param __x A %exponential_distribution random number distribution.
2193 *
2194 * @returns The output stream with the state of @p __x inserted or in
2195 * an error state.
2196 */
2197 template<typename _RealType1, typename _CharT, typename _Traits>
2198 friend std::basic_ostream<_CharT, _Traits>&
2199 operator<<(std::basic_ostream<_CharT, _Traits>& __os,
2200 const exponential_distribution<_RealType1>& __x);
2201
2202 /**
2203 * Extracts a %exponential_distribution random number distribution
2204 * @p __x from the input stream @p __is.
2205 *
2206 * @param __is An input stream.
2207 * @param __x A %exponential_distribution random number
2208 * generator engine.
2209 *
2210 * @returns The input stream with @p __x extracted or in an error state.
2211 */
2212 template<typename _CharT, typename _Traits>
2213 friend std::basic_istream<_CharT, _Traits>&
2214 operator>>(std::basic_istream<_CharT, _Traits>& __is,
2215 exponential_distribution& __x)
2216 { return __is >> __x._M_lambda; }
2217
2218 private:
2219 result_type _M_lambda;
2220 };
2221
2222
2223 /**
2224 * @brief A normal continuous distribution for random numbers.
2225 *
2226 * The formula for the normal probability mass function is
2227 * @f$ p(x) = \frac{1}{\sigma \sqrt{2 \pi}}
2228 * e^{- \frac{{x - mean}^ {2}}{2 \sigma ^ {2}} } @f$.
2229 */
2230 template<typename _RealType = double>
2231 class normal_distribution
2232 {
2233 public:
2234 // types
2235 typedef _RealType input_type;
2236 typedef _RealType result_type;
2237
2238 public:
2239 /**
2240 * Constructs a normal distribution with parameters @f$ mean @f$ and
2241 * @f$ \sigma @f$.
2242 */
2243 explicit
2244 normal_distribution(const result_type& __mean = result_type(0),
2245 const result_type& __sigma = result_type(1))
2246 : _M_mean(__mean), _M_sigma(__sigma), _M_saved_available(false)
2247 {
2248 _GLIBCXX_DEBUG_ASSERT(_M_sigma > 0);
2249 }
2250
2251 /**
2252 * Gets the mean of the distribution.
2253 */
2254 _RealType
2255 mean() const
2256 { return _M_mean; }
2257
2258 /**
2259 * Gets the @f$ \sigma @f$ of the distribution.
2260 */
2261 _RealType
2262 sigma() const
2263 { return _M_sigma; }
2264
2265 /**
2266 * Resets the distribution.
2267 */
2268 void
2269 reset()
2270 { _M_saved_available = false; }
2271
2272 template<class _UniformRandomNumberGenerator>
2273 result_type
2274 operator()(_UniformRandomNumberGenerator& __urng);
2275
2276 /**
2277 * Inserts a %normal_distribution random number distribution
2278 * @p __x into the output stream @p __os.
2279 *
2280 * @param __os An output stream.
2281 * @param __x A %normal_distribution random number distribution.
2282 *
2283 * @returns The output stream with the state of @p __x inserted or in
2284 * an error state.
2285 */
2286 template<typename _RealType1, typename _CharT, typename _Traits>
2287 friend std::basic_ostream<_CharT, _Traits>&
2288 operator<<(std::basic_ostream<_CharT, _Traits>& __os,
2289 const normal_distribution<_RealType1>& __x);
2290
2291 /**
2292 * Extracts a %normal_distribution random number distribution
2293 * @p __x from the input stream @p __is.
2294 *
2295 * @param __is An input stream.
2296 * @param __x A %normal_distribution random number generator engine.
2297 *
2298 * @returns The input stream with @p __x extracted or in an error state.
2299 */
2300 template<typename _RealType1, typename _CharT, typename _Traits>
2301 friend std::basic_istream<_CharT, _Traits>&
2302 operator>>(std::basic_istream<_CharT, _Traits>& __is,
2303 normal_distribution<_RealType1>& __x);
2304
2305 private:
2306 result_type _M_mean;
2307 result_type _M_sigma;
2308 result_type _M_saved;
2309 bool _M_saved_available;
2310 };
2311
2312
2313 /**
2314 * @brief A gamma continuous distribution for random numbers.
2315 *
2316 * The formula for the gamma probability mass function is
2317 * @f$ p(x) = \frac{1}{\Gamma(\alpha)} x^{\alpha - 1} e^{-x} @f$.
2318 */
2319 template<typename _RealType = double>
2320 class gamma_distribution
2321 {
2322 public:
2323 // types
2324 typedef _RealType input_type;
2325 typedef _RealType result_type;
2326
2327 public:
2328 /**
2329 * Constructs a gamma distribution with parameters @f$ \alpha @f$.
2330 */
2331 explicit
2332 gamma_distribution(const result_type& __alpha_val = result_type(1))
2333 : _M_alpha(__alpha_val)
2334 {
2335 _GLIBCXX_DEBUG_ASSERT(_M_alpha > 0);
2336 _M_initialize();
2337 }
2338
2339 /**
2340 * Gets the @f$ \alpha @f$ of the distribution.
2341 */
2342 _RealType
2343 alpha() const
2344 { return _M_alpha; }
2345
2346 /**
2347 * Resets the distribution.
2348 */
2349 void
2350 reset() { }
2351
2352 template<class _UniformRandomNumberGenerator>
2353 result_type
2354 operator()(_UniformRandomNumberGenerator& __urng);
2355
2356 /**
2357 * Inserts a %gamma_distribution random number distribution
2358 * @p __x into the output stream @p __os.
2359 *
2360 * @param __os An output stream.
2361 * @param __x A %gamma_distribution random number distribution.
2362 *
2363 * @returns The output stream with the state of @p __x inserted or in
2364 * an error state.
2365 */
2366 template<typename _RealType1, typename _CharT, typename _Traits>
2367 friend std::basic_ostream<_CharT, _Traits>&
2368 operator<<(std::basic_ostream<_CharT, _Traits>& __os,
2369 const gamma_distribution<_RealType1>& __x);
2370
2371 /**
2372 * Extracts a %gamma_distribution random number distribution
2373 * @p __x from the input stream @p __is.
2374 *
2375 * @param __is An input stream.
2376 * @param __x A %gamma_distribution random number generator engine.
2377 *
2378 * @returns The input stream with @p __x extracted or in an error state.
2379 */
2380 template<typename _CharT, typename _Traits>
2381 friend std::basic_istream<_CharT, _Traits>&
2382 operator>>(std::basic_istream<_CharT, _Traits>& __is,
2383 gamma_distribution& __x)
2384 {
2385 __is >> __x._M_alpha;
2386 __x._M_initialize();
2387 return __is;
2388 }
2389
2390 private:
2391 void
2392 _M_initialize();
2393
2394 result_type _M_alpha;
2395
2396 // Hosts either lambda of GB or d of modified Vaduva's.
2397 result_type _M_l_d;
2398 };
2399
2400 /* @} */ // group tr1_random_distributions_continuous
2401 /* @} */ // group tr1_random_distributions
2402 /* @} */ // group tr1_random
2403
2404 _GLIBCXX_END_NAMESPACE_TR1
2405 }
2406
2407 #include <tr1_impl/random.tcc>
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