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/* rng.h : definitions for using Don Knuth's random number generator.
To use it:
1. Call ran_init(seed) with any long seed. (Optional,
but you will always get the same sequence otherwise.)
2. Use NEXTRAN to get the next number (0..2^30-1).
Alternatively, use KRAN(k) to get a random number 0..k-1.
For large k, KRAN(k) is not quite uniform. In that case
use GETKRAN(k,var) to set the variable var to a better
random number 0..k-1.
Some of these definitions are also in naututil.h.
*/
#ifdef __cplusplus
extern "C" {
#endif
extern long *ran_arr_ptr;
long ran_arr_cycle(void);
void ran_init(long seed);
void ran_array(long *aa, int n);
#ifdef __cplusplus
}
#endif
#define MAXRAN (0x3fffffffL) /* Values are 0..MAXRAN */
#define NEXTRAN (*ran_arr_ptr>=0 ? *ran_arr_ptr++ : ran_arr_cycle())
#define KRAN(k) (NEXTRAN%(k))
#define RANREAL ((NEXTRAN+0.5)/(MAXRAN+1.0)) /* Uniform (0,1) */
#define MAXSAFE(k) (((MAXRAN+1)/(k))*(k))
#define GETKRAN(k,var) {long __getkran; \
do {__getkran = NEXTRAN;} while (__getkran >= MAXSAFE(k)); \
var = __getkran % (k);}
#define INITRANBYTIME ran_init((long)time(NULL))
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