DLAPLL(1) LAPACK auxiliary routine (version 3.2) DLAPLL(1)NAME
DLAPLL - two column vectors X and Y, let A = ( X Y )
SUBROUTINE DLAPLL( N, X, INCX, Y, INCY, SSMIN )
INTEGER INCX, INCY, N
DOUBLE PRECISION SSMIN
DOUBLE PRECISION 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) DOUBLE PRECISION 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) DOUBLE PRECISION 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 ).
LAPACK auxiliary routine (versioNovember 2008 DLAPLL(1)