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/*********************************************************************/
/* */
/* current processor time in seconds */
/* difference between two calls is processor time spent by your code */
/* needs: <sys/types.h>, <sys/times.h> */
/* depends on compiler and OS */
/* */
/*********************************************************************/
#include <sys/types.h>
#include <sys/times.h>
/*
* Prototypes.
*/
unsigned long timer(void);
void init_rand(long);
double rand01(void);
double randg01(void);
long nrand(long);
void free_arc(void *);
unsigned long timer ()
{ struct tms hold;
times(&hold);
return (unsigned long) ((float) (hold.tms_utime) / 60.0);
}
/*********************************************************************/
/* */
/* Family of random number generators */
/* */
/* Initialisation: */
/* void init_rand ( seed ); */
/* long seed - any positive number */
/* if seed<=0 init_rand takes time */
/* from timer instead of seed */
/* */
/* Whole number uniformly distributed on [0,n): */
/* long nrand (n); */
/* long n */
/* */
/* Real number uniformly distributed on [0,1] */
/* double rand01(); */
/* */
/* Real number with Gauss(0,1) disitribution: */
/* double randg01(); */
/* */
/* Algorithm: */
/* x(n+1) = (x(n) * 5^13) mod 2^31 */
/* */
/*********************************************************************/
unsigned long internal_seed;
void init_rand ( init_seed )
long init_seed;
{ internal_seed = ( init_seed > 0 )
? (unsigned long) init_seed
: (unsigned long) timer();
/* only odd numbers are acceptable */
if ( internal_seed % 2 == 0 ) internal_seed --;
}
/*********************************************************************/
/* */
/* Internal function irand may depend on OS and compiler */
/* */
/* irand assumption: */
/* unsigned long i,j; */
/* if i*j > max(unsigned long) */
/* 1. No overflow interruption */
/* 2. i*j = i*j mod max(unsigned long) */
/* */
/* This assumption is true for a lot of computers. */
/* If your computer fails: */
/* rename: irand <---> xrand */
/* */
/*********************************************************************/
#define A 1220703125
#define B 2147483647
#define BF 2147483647.
static long irand ()
{ internal_seed = ( internal_seed * A ) & B;
return (long) internal_seed ;
}
#if 0 /* Not used. */
/*********************************************************************/
/* */
/* computer independent variant of irand */
/* */
/*********************************************************************/
#define T15 32768
#define T16 65536
#define A1 37252
#define A2 29589
static long xrand()
{ unsigned long is1, is2;
is1 = internal_seed / T15;
is2 = internal_seed % T15;
internal_seed = ( (((is2 * A1) + (is1 * A2))% T16 )* T15 + (is2 * A2) ) & B;
return (long) ( internal_seed ) ;
}
#endif
/*********************************************************************/
double rand01()
{ return (double) (irand() / BF) ;
}
/*********************************************************************/
#define NK 12
double randg01()
{ int i;
double sum = 0;
for ( i = 0; i < NK; i++ ) sum += rand01();
return sum - 6.;
/* if NK != 12 then you must return (12/NK)*sum - (NK/2) */
}
#undef NK
/*********************************************************************/
long nrand ( n )
long n;
{ return (long) ( rand01() * (double) n );
}
/*********************************************************************/
#undef A
#undef A1
#undef A2
#undef B
#undef BF
#undef T15
#undef T16
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