polcoe.c

Numerical Recipes in C的源代码

#include "nrutil.h"

void polcoe(x,y,n,cof)
float cof[],x[],y[];
int n;
{
	int k,j,i;
	float phi,ff,b,*s;

	s=vector(0,n);
	for (i=0;i<=n;i++) s[i]=cof[i]=0.0;
	s[n] = -x[0];
	for (i=1;i<=n;i++) {
		for (j=n-i;j<=n-1;j++)
			s[j] -= x[i]*s[j+1];
		s[n] -= x[i];
	}
	for (j=0;j<=n;j++) {
		phi=n+1;
		for (k=n;k>=1;k--)
			phi=k*s[k]+x[j]*phi;
		ff=y[j]/phi;
		b=1.0;
		for (k=n;k>=0;k--) {
			cof[k] += b*ff;
			b=s[k]+x[j]*b;
		}
	}
	free_vector(s,0,n);
}