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/* 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;
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