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/*
*
* Copyright (C) 2010 - DIGITEO - Michael Baudin
* Copyright (C) 2004 - Bruno Pincon
* Copyright (C) 1973 - CLEVE B. MOLER
* Copyright (C) 1973 - MICHAEL A. MALCOLM
*
* PURPOSE
* the basic rand generator of Scilab : s <- (a*s + c) mod m
* with :
* m = 2^{31}
* a = 843314861
* c = 453816693
*
* s must be in [0,m-1] when user changes seed with set_state_urand
* period = m
*
* NOTES
* a/ Rewritten (in C) so as to output integers like all the others
* generators (and also to have the same manner to set/get the state)
* b/ unsigned int arithmetic must be the classic 32 bits unsigned
* arithmetic (ie also is exact modulo 2^32).
*
* URAND, A UNIVERSAL RANDOM NUMBER GENERATOR
* BY, MICHAEL A. MALCOLM, CLEVE B. MOLER,
* STAN-CS-73-334, JANUARY 1973,
* COMPUTER SCIENCE DEPARTMENT,
* School of Humanities and Sciences, STANFORD UNIVERSITY,
* ftp://reports.stanford.edu/pub/cstr/reports/cs/tr/73/334/CS-TR-73-334.pdf
*
*
*/
#include <math.h> /* to use floor */
#include "sciprint.h"
#include "others_generators.h"
#include "localization.h"
static unsigned int s = 0;
unsigned long int urandc(void)
{
s = 843314861ul * s + 453816693ul; /* => on obtient ici un resultat modulo 2^32 */
/* il suffit du test suivant pour obtenir le modulo 2^31 */
if (s >= 2147483648ul)
{
s -= 2147483648ul;
}
return ( s );
}
int set_state_urand(double g)
{
if ( g == floor(g) && 0 <= g && g <= 2147483647 )
{
s = (unsigned int) g;
return ( 1 );
}
else
{
sciprint(_("\nBad seed for urand, must be an int in [0, 2147483647]\n"));
return ( 0 );
}
}
void get_state_urand(double g[])
{
g[0] = (double) s;
}
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