ZLAPLL(3F) ZLAPLL(3F)
ZLAPLL - two column vectors X and Y, let A = ( X Y )
SUBROUTINE ZLAPLL( N, X, INCX, Y, INCY, SSMIN )
INTEGER INCX, INCY, N
DOUBLE PRECISION SSMIN
COMPLEX*16 X( * ), Y( * )
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.
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 ).
ZLAPLL(3F) ZLAPLL(3F)
ZLAPLL - two column vectors X and Y, let A = ( X Y )
SUBROUTINE ZLAPLL( N, X, INCX, Y, INCY, SSMIN )
INTEGER INCX, INCY, N
DOUBLE PRECISION SSMIN
COMPLEX*16 X( * ), Y( * )
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.
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 ).
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