zlapll(3)

NAME

ZLAPLL - two column vectors X and Y, let A = ( X Y )

SYNOPSIS

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 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.

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 ).

LAPACK version 3.0 15 June 2000

ZLAPLL(3)