diff options
Diffstat (limited to 'gsl-1.9/rng/fishman20.c')
-rw-r--r-- | gsl-1.9/rng/fishman20.c | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/gsl-1.9/rng/fishman20.c b/gsl-1.9/rng/fishman20.c new file mode 100644 index 0000000..9851f13 --- /dev/null +++ b/gsl-1.9/rng/fishman20.c @@ -0,0 +1,103 @@ +/* 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; |