BlockIP
Functions
ritz_value.h File Reference

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Functions

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

Function Documentation

int ritz_value ( int  itcg,
double *  valpha,
double *  vbeta 
)
Parameters
itcgThe order of the matrix
valphaOn entry, the itcg diagonal elements of the tridiagonal matrix. On exit, if info = 0, the eigenvalues in ascending order
vbetaOn 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