orthog.c

Numerical Recipes in C的源代码

#define NRANSI
#include "nrutil.h"

void orthog(int n, float anu[], float alpha[], float beta[], float a[],
	float b[])
{
	int k,l;
	float **sig;
	int looptmp;

	sig=matrix(1,2*n+1,1,2*n+1);
	looptmp=2*n;
	for (l=3;l<=looptmp;l++) sig[1][l]=0.0;
	looptmp++;
	for (l=2;l<=looptmp;l++) sig[2][l]=anu[l-1];
	a[1]=alpha[1]+anu[2]/anu[1];
	b[1]=0.0;
	for (k=3;k<=n+1;k++) {
		looptmp=2*n-k+3;
		for (l=k;l<=looptmp;l++) {
			sig[k][l]=sig[k-1][l+1]+(alpha[l-1]-a[k-2])*sig[k-1][l]-
				b[k-2]*sig[k-2][l]+beta[l-1]*sig[k-1][l-1];
		}
		a[k-1]=alpha[k-1]+sig[k][k+1]/sig[k][k]-sig[k-1][k]/sig[k-1][k-1];
		b[k-1]=sig[k][k]/sig[k-1][k-1];
	}
	free_matrix(sig,1,2*n+1,1,2*n+1);
}
#undef NRANSI