lis_array_qr.3f man page

lis_array_qr ā€” calculate the eigenvalues with the QR algorithm

Synopsis

subroutine lis_array_cgs(LIS_INTEGER n, LIS_SCALAR a(), LIS_SCALAR q(), LIS_SCALAR r(), LIS_INTEGER qriter, LIS_SCALAR qrerr, LIS_INTEGER ierr);

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

See Also

lis(3)

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

Info

1 Nov 2014 Man Page Lis Library Functions