subroutine dlapll (N, X, INCX, Y, INCY, SSMIN)
DLAPLL measures the linear dependence of two vectors.
DLAPLL measures the linear dependence of two vectors.
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:
N is INTEGER The length of the vectors X and Y.
X
X is DOUBLE PRECISION array, dimension (1+(N-1)*INCX) On entry, X contains the N-vector X. On exit, X is overwritten.
INCX
INCX is INTEGER The increment between successive elements of X. INCX > 0.
Y
Y is DOUBLE PRECISION array, dimension (1+(N-1)*INCY) On entry, Y contains the N-vector Y. On exit, Y is overwritten.
INCY
INCY is INTEGER The increment between successive elements of Y. INCY > 0.
SSMIN
SSMIN is DOUBLE PRECISION The smallest singular value of the N-by-2 matrix A = ( X Y ).
Author:
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
Definition at line 104 of file dlapll.f.
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