| /* rng/vax.c |
| * |
| * Copyright (C) 1996, 1997, 1998, 1999, 2000 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 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. |
| */ |
| |
| #include <config.h> |
| #include <stdlib.h> |
| #include <gsl/gsl_rng.h> |
| |
| /* This is the old vax generator MTH$RANDOM. The sequence is, |
| |
| x_{n+1} = (a x_n + c) mod m |
| |
| with a = 69069, c = 1 and m = 2^32. The seed specifies the initial |
| value, x_1. |
| |
| The theoretical value of x_{10001} is 3051034865. |
| |
| The period of this generator is 2^32. */ |
| |
| static inline unsigned long int vax_get (void *vstate); |
| static double vax_get_double (void *vstate); |
| static void vax_set (void *state, unsigned long int s); |
| |
| typedef struct |
| { |
| unsigned long int x; |
| } |
| vax_state_t; |
| |
| static inline unsigned long int |
| vax_get (void *vstate) |
| { |
| vax_state_t *state = (vax_state_t *) vstate; |
| |
| state->x = (69069 * state->x + 1) & 0xffffffffUL; |
| |
| return state->x; |
| } |
| |
| static double |
| vax_get_double (void *vstate) |
| { |
| return vax_get (vstate) / 4294967296.0 ; |
| } |
| |
| static void |
| vax_set (void *vstate, unsigned long int s) |
| { |
| vax_state_t *state = (vax_state_t *) vstate; |
| |
| /* default seed is 0. The constant term c stops the series from |
| collapsing to 0,0,0,0,0,... */ |
| |
| state->x = s; |
| |
| return; |
| } |
| |
| static const gsl_rng_type vax_type = |
| {"vax", /* name */ |
| 0xffffffffUL, /* RAND_MAX */ |
| 0, /* RAND_MIN */ |
| sizeof (vax_state_t), |
| &vax_set, |
| &vax_get, |
| &vax_get_double}; |
| |
| const gsl_rng_type *gsl_rng_vax = &vax_type; |