lis_array_qr man page

lis_array_qr — calculate the eigenvalues with the QR algorithm

Synopsis

#include "lis.h"

LIS_INT lis_array_qr(LIS_INT n, LIS_SCALAR a[], LIS_SCALAR q[], LIS_SCALAR r[], LIS_INT *qriter, LIS_SCALAR *qrerr);

Description

Calculate the eigenvalues of matrix A with the QR algorithm.

Input

n
The size of the matrices
a
The array that stores matrix A of size n * n
q
The work array Q of size n * n
r
The work array R of size n * n

Output

a
The array that stores the block upper-triangular matrix with eigenvalues in the block diagonal elements after similarity transformation
qriter
The number of iterations of the QR algorithm
qrerr
The 2-norm of the first subdiagonal element A(2,1) after similarity transformation

Exit Status

The following exit values are returned:

0
The process is normally terminated
unspecified
An error occurred

See Also

lis(3)

http://www.ssisc.org/lis/

Info

1 Nov 2014 Man Page Lis Library Functions