ritz_value.C File Reference

#include <stdio.h>
#include <math.h>

Macros
#define	DSTERF   dsterf_

Functions
void	DSTERF (int *n, double *d, double *e, int *info)
int	ritz_value (int itcg, double *valpha, double *vbeta)

Macro Definition Documentation

#define DSTERF   dsterf_

Function Documentation

void DSTERF	(	int *	n,
		double *	d,
		double *	e,
		int *	info
	)

int ritz_value	(	int	itcg,
		double *	valpha,
		double *	vbeta
	)

Parameters

itcg	The order of the matrix
valpha	On entry, the itcg diagonal elements of the tridiagonal matrix. On exit, if info = 0, the eigenvalues in ascending order
vbeta	On entry, the (itcg-1) subdiagonal elements of the tridiagonal matrix. On exit, vbeta has been destroyed.

Returns

= 0: successful exit < 0: if -i, the i-th argument had an illegal value > 0: the algorithm failed to find all of the eigenvalues in a total of 30*itcg iterations; if i, then i elements of vbeta have not converged to zero.

Note

The user must guarantee valpha and vbeta have at least dimension itcg