xfit.c

Numerical Recipes in C的源代码

/* Driver for routine fit */

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

#define NPT 100
#define SPREAD 0.5

int main(void)
{
	long idum=(-117);
	int i,mwt;
	float a,b,chi2,q,siga,sigb,*x,*y,*sig;

	x=vector(1,NPT);
	y=vector(1,NPT);
	sig=vector(1,NPT);
	for (i=1;i<=NPT;i++) {
		x[i]=0.1*i;
		y[i] = -2.0*x[i]+1.0+SPREAD*gasdev(&idum);
		sig[i]=SPREAD;
	}
	for (mwt=0;mwt<=1;mwt++) {
		fit(x,y,NPT,sig,mwt,&a,&b,&siga,&sigb,&chi2,&q);
		if (mwt == 0)
			printf("\nIgnoring standard deviations\n");
		else
			printf("\nIncluding standard deviations\n");
		printf("%12s %9.6f %18s %9.6f \n",
			"a  =  ",a,"uncertainty:",siga);
		printf("%12s %9.6f %18s %9.6f \n",
			"b  =  ",b,"uncertainty:",sigb);
		printf("%19s %14.6f \n","chi-squared: ",chi2);
		printf("%23s %10.6f \n","goodness-of-fit: ",q);
	}
	free_vector(sig,1,NPT);
	free_vector(y,1,NPT);
	free_vector(x,1,NPT);
	return 0;
}
#undef NRANSI