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comparison egglib/egglib-2.1.5/include/egglib-cpp/Random.hpp @ 1:420b57c3c185 draft

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date Fri, 10 Jul 2015 04:39:30 -0400
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0:3e19d0dfcf3e 1:420b57c3c185
1 /*
2 Copyright 2008,2009,2012 Stéphane De Mita, Mathieu Siol
3 Adapted from MStrat, developed by Charles-Edouard Coste,
4 Thomas M. Bataillon, Mathieu Cotisson, Guy Decoux, Chistophe Rozale,
5 Daniel J. Schoen and Jacques L. David.
6
7 This file is part of the EggLib library.
8
9 EggLib is free software: you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation, either version 3 of the License, or
12 (at your option) any later version.
13
14 EggLib is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
18
19 You should have received a copy of the GNU General Public License
20 along with EggLib. If not, see <http://www.gnu.org/licenses/>.
21 */
22
23 #ifndef EGGLIB_RANDOM_HPP
24 #define EGGLIB_RANDOM_HPP
25
26 namespace egglib {
27
28 /** \brief Pseudo-random number generator
29 *
30 * \ingroup core
31 *
32 * Random is a pseudo-random number generator, adapted from a part of MStrat,
33 * developed by Charles-Edouard Coste, Thomas M. Bataillon, Mathieu Cotisson,
34 * Guy Decoux, Chistophe Rozale, Daniel J. Schoen and Jacques L. David.
35 *
36 * It uses two different seeds. By default, they are initialized to available
37 * arbitrary values. However, a given sequence can be repeated by passing the
38 * same two seeds.
39 *
40 */
41 class Random {
42 public:
43 /** \brief Initializes using default seeds
44 *
45 * Uses the current system time and the memory address of the object as an attempt to generate unique sequences.
46 */
47 Random();
48
49 /** \brief Initializes using given seeds
50 *
51 * This constructor can be used to reproduce a given sequence.
52 */
53 Random(double seed1, double seed2);
54
55 /** \brief Draws a number from an exponential distribution
56 *
57 * \param expectation the distribution mean (also 1/lambda
58 * where lambda is the rate parameter).
59 *
60 */
61 double erand(double expectation);
62
63 /** \brief Draws an integer from a uniform distribution bound by 0 and max (max is not included)
64 *
65 * max is not included.
66 *
67 */
68 unsigned int irand(unsigned int max);
69
70 /** \brief Draws an integer from a Poisson distribution with parameter p
71 *
72 * The Poisson transformation algorithm was taken from (in French)
73 * http://www.u-picardie.fr/~cochard/IEM/demos/C107/C107_3.htm.
74 */
75 unsigned int prand(double p);
76
77 /** \brief Draws a number from a normal distribution of expectation 0 and variance 1
78 *
79 * The algorithm used is the polar form of the Box-Muller
80 * algorithm. \todo use the Ziggurat algorithm for the
81 * nrand() method of Random.
82 *
83 */
84 double nrand();
85
86 /** \brief Draws a number from a geometric law
87 *
88 * \param param the parameter of the law
89 *
90 */
91 unsigned int grand(double);
92
93 /** \brief Draws a number from a uniform distribution between 0 and 1
94 *
95 */
96 double uniform();
97
98 /** \brief Gets the current value of the first seed
99 *
100 */
101 double seed1() const;
102
103 /** \brief Gets the current value of the second seed
104 *
105 */
106 double seed2() const;
107
108 /** \brief Sets the current value of the first seed
109 *
110 */
111 void seed1(double);
112
113 /** \brief Sets the current value of the second seed
114 *
115 */
116 void seed2(double);
117
118 private:
119 // First seed
120 double _seed1;
121
122 // Second seed
123 double _seed2;
124
125 /* since the normal random generator draws two numbers at
126 * a time, one is cached and returned at any subsequent call
127 */
128 bool b_ncached;
129 double v_ncached;
130
131 };
132 }
133
134 #endif