1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
|
/* rng/ran1.c
*
* Copyright (C) 1996, 1997, 1998, 1999, 2000, 2007 James Theiler, Brian Gough
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or (at
* your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include <config.h>
#include <stdlib.h>
#include <gsl/gsl_rng.h>
/* This is an implementation of the algorithm used in Numerical
Recipe's ran1 generator. It is MINSTD with a 32-element
shuffle-box. */
static inline unsigned long int ran1_get (void *vstate);
static double ran1_get_double (void *vstate);
static void ran1_set (void *state, unsigned long int s);
static const long int m = 2147483647, a = 16807, q = 127773, r = 2836;
#define N_SHUFFLE 32
#define N_DIV (1 + 2147483646/N_SHUFFLE)
typedef struct
{
unsigned long int x;
unsigned long int n;
unsigned long int shuffle[N_SHUFFLE];
}
ran1_state_t;
static inline unsigned long int
ran1_get (void *vstate)
{
ran1_state_t *state = (ran1_state_t *) vstate;
const unsigned long int x = state->x;
const long int h = x / q;
const long int t = a * (x - h * q) - h * r;
if (t < 0)
{
state->x = t + m;
}
else
{
state->x = t;
}
{
unsigned long int j = state->n / N_DIV;
state->n = state->shuffle[j];
state->shuffle[j] = state->x;
}
return state->n;
}
static double
ran1_get_double (void *vstate)
{
float x_max = 1 - 1.2e-7f ; /* Numerical Recipes version of 1-FLT_EPS */
float x = ran1_get (vstate) / 2147483647.0f ;
if (x > x_max)
return x_max ;
return x ;
}
static void
ran1_set (void *vstate, unsigned long int s)
{
ran1_state_t *state = (ran1_state_t *) vstate;
int i;
if (s == 0)
s = 1; /* default seed is 1 */
for (i = 0; i < 8; i++)
{
long int h = s / q;
long int t = a * (s - h * q) - h * r;
if (t < 0)
t += m;
s = t;
}
for (i = N_SHUFFLE - 1; i >= 0; i--)
{
long int h = s / q;
long int t = a * (s - h * q) - h * r;
if (t < 0)
t += m;
s = t;
state->shuffle[i] = s;
}
state->x = s;
state->n = s;
return;
}
static const gsl_rng_type ran1_type =
{"ran1", /* name */
2147483646, /* RAND_MAX */
1, /* RAND_MIN */
sizeof (ran1_state_t),
&ran1_set,
&ran1_get,
&ran1_get_double};
const gsl_rng_type *gsl_rng_ran1 = &ran1_type;
|
