zlapll3lapack
Two column vectors x and y, let a = ( x y )
Usage
- SUBROUTINE ZLAPLL(
-
N, X, INCX, Y, INCY, SSMIN )
- INTEGER
-
INCX, INCY, N
- DOUBLE
-
PRECISION SSMIN
- COMPLEX*16
-
X( * ), Y( * )
Purpose
Given two column vectors X and Y, let The subroutine first computes the QR factorization of A = Q*R, and then computes the SVD of the 2-by-2 upper triangular matrix R. The smaller singular value of R is returned in SSMIN, which is used as the measurement of the linear dependency of the vectors X and Y.
Arguments
N (input) INTEGER
|
The length of the vectors X and Y. |
|---|---|
X (input/output) COMPLEX*16 array, dimension (1+(N-1)*INCX)
|
On entry, X contains the N-vector X. On exit, X is overwritten. |
INCX (input) INTEGER
|
The increment between successive elements of X. INCX > 0. |
Y (input/output) COMPLEX*16 array, dimension (1+(N-1)*INCY)
|
On entry, Y contains the N-vector Y. On exit, Y is overwritten. |
INCY (input) INTEGER
|
The increment between successive elements of Y. INCY > 0. |
SSMIN (output) DOUBLE PRECISION
|
The smallest singular value of the N-by-2 matrix A = ( X Y ). |