xirbit2.c

Numerical Recipes in C的源代码

/* Driver for routine irbit2 */

#include <stdio.h>
#define NRANSI
#include "nr.h"

#define NBIN 15
#define NTRIES 10000

static unsigned long twoton[16]={0x1L,0x2L,0x4L,0x8L,0x10L,0x20L,0x40L,0x80L,
	0x100L,0x200L,0x400L,0x800L,0x1000L,0x2000L,0x4000L,0x8000L};

int main(void)
{
	int i,iflg,ipts=0,j,n;
	unsigned long iseed=111;
	float delay[NBIN+1];

	/* Calculate distribution of runs of zeros */
	for (i=1;i<=NBIN;i++) delay[i]=0.0;
	for (i=1;i<=NTRIES;i++) {
		if (irbit2(&iseed) == 1) {
			++ipts;
			iflg=0;
			for (j=1;j<=NBIN;j++) {
				if ((irbit2(&iseed) == 1) && (iflg == 0)) {
					iflg=1;
					++delay[j];
				}
			}
		}
	}
	printf("distribution of runs of n zeros\n");
	printf("%6s %22s %18s \n","n","probability","expected");
	for (n=1;n<=NBIN;n++)
		printf("%6d %19.4f %20.4f\n",
			(n-1),delay[n]/ipts,1.0/(double)twoton[n]);
	return 0;
}
#undef NRANSI