| /* rng/fishman20.c |
| * |
| * 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 2 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. |
| */ |
| |
| /* |
| * This generator is taken from |
| * |
| * Donald E. Knuth |
| * The Art of Computer Programming |
| * Volume 2 |
| * Third Edition |
| * Addison-Wesley |
| * Page 108 |
| * |
| * It is called "Fishman" |
| * |
| * This implementation copyright (C) 2001 Carlo Perassi |
| * and (C) 2003 Heiko Bauke. |
| */ |
| |
| #include <config.h> |
| #include <stdlib.h> |
| #include <gsl/gsl_rng.h> |
| |
| static inline unsigned long int ran_get (void *vstate); |
| static double ran_get_double (void *vstate); |
| static void ran_set (void *state, unsigned long int s); |
| |
| static const long int m = 2147483647, a = 48271, q = 44488, r = 3399; |
| |
| typedef struct |
| { |
| unsigned long int x; |
| } |
| ran_state_t; |
| |
| static inline unsigned long int |
| ran_get (void *vstate) |
| { |
| ran_state_t *state = (ran_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; |
| } |
| |
| return state->x; |
| } |
| |
| static double |
| ran_get_double (void *vstate) |
| { |
| ran_state_t *state = (ran_state_t *) vstate; |
| |
| return ran_get (state) / 2147483647.0; |
| } |
| |
| static void |
| ran_set (void *vstate, unsigned long int s) |
| { |
| ran_state_t *state = (ran_state_t *) vstate; |
| |
| if ((s%m) == 0) |
| s = 1; /* default seed is 1 */ |
| |
| state->x = s & m; |
| |
| return; |
| } |
| |
| static const gsl_rng_type ran_type = { |
| "fishman20", /* name */ |
| 2147483646, /* RAND_MAX */ |
| 1, /* RAND_MIN */ |
| sizeof (ran_state_t), |
| &ran_set, |
| &ran_get, |
| &ran_get_double |
| }; |
| |
| const gsl_rng_type *gsl_rng_fishman20 = &ran_type; |