xchstwo.c

Numerical Recipes in C的源代码

/* Driver for routine chstwo */

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

#define NBINS 10
#define NPTS 2000

int main(void)
{
	long idum=(-17);
	int i,ibin,j;
	float chsq,df,prob,x,*bins1,*bins2;

	bins1=vector(1,NBINS);
	bins2=vector(1,NBINS);
	for (j=1;j<=NBINS;j++) {
		bins1[j]=0.0;
		bins2[j]=0.0;
	}
	for (i=1;i<=NPTS;i++) {
		x=expdev(&idum);
		ibin=(int) (x*NBINS/3.0+1);
		if (ibin <= NBINS) ++bins1[ibin];
		x=expdev(&idum);
		ibin=(int) (x*NBINS/3.0+1);
		if (ibin <= NBINS) ++bins2[ibin];
	}
	chstwo(bins1,bins2,NBINS,0,&df,&chsq,&prob);
	printf("\n%15s %15s\n","dataset 1","dataset 2");
	for (i=1;i<=NBINS;i++)
		printf("%13.2f %15.2f\n",bins1[i],bins2[i]);
	printf("\n%18s %12.4f\n","chi-squared:",chsq);
	printf("%18s %12.4f\n","probability:",prob);
	free_vector(bins2,1,NBINS);
	free_vector(bins1,1,NBINS);
	return 0;
}
#undef NRANSI