xmedfit.c

Numerical Recipes in C的源代码

/* Driver for routine medfit */

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

#define NPT 100
#define SPREAD 0.1
#define NDATA NPT

int main(void)
{
	long idum=(-1984);
	int i,mwt=1;
	float a,abdev,b,chi2,q,siga,sigb;
	float *x,*y,*sig;

	x=vector(1,NDATA);
	y=vector(1,NDATA);
	sig=vector(1,NDATA);
	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;
	}
	fit(x,y,NPT,sig,mwt,&a,&b,&siga,&sigb,&chi2,&q);
	printf("\nAccording to routine FIT the result is:\n");
	printf("   a =  %8.4f   uncertainty:  %8.4f\n",a,siga);
	printf("   b =  %8.4f   uncertainty:  %8.4f\n",b,sigb);
	printf("   chi-squared:  %8.4f  for  %4d  points\n",chi2,NPT);
	printf("   goodness-of-fit:  %8.4f\n",q);
	printf("\nAccording to routine MEDFIT the result is:\n");
	medfit(x,y,NPT,&a,&b,&abdev);
	printf("   a =  %8.4f\n",a);
	printf("   b =  %8.4f\n",b);
	printf("   absolute deviation (per data point): %8.4f\n",abdev);
	printf("   (note: gaussian SPREAD is %8.4f)\n",SPREAD);
	free_vector(sig,1,NDATA);
	free_vector(y,1,NDATA);
	free_vector(x,1,NDATA);
	return 0;
}
#undef NRANSI