zlapll()

subroutine zlapll	(	integer	n,
		complex*16, dimension( * )	x,
		integer	incx,
		complex*16, dimension( * )	y,
		integer	incy,
		double precision	ssmin )

ZLAPLL measures the linear dependence of two vectors.

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Purpose:

!>
!> Given two column vectors X and Y, let
!>
!>                      A = ( X Y ).
!>
!> 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.
!> 

Parameters

[in]	N	!> N is INTEGER !> The length of the vectors X and Y. !>
[in,out]	X	!> X is COMPLEX*16 array, dimension (1+(N-1)*INCX) !> On entry, X contains the N-vector X. !> On exit, X is overwritten. !>
[in]	INCX	!> INCX is INTEGER !> The increment between successive elements of X. INCX > 0. !>
[in,out]	Y	!> Y is COMPLEX*16 array, dimension (1+(N-1)*INCY) !> On entry, Y contains the N-vector Y. !> On exit, Y is overwritten. !>
[in]	INCY	!> INCY is INTEGER !> The increment between successive elements of Y. INCY > 0. !>
[out]	SSMIN	!> SSMIN is DOUBLE PRECISION !> The smallest singular value of the N-by-2 matrix A = ( X Y ). !>

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.