dlapll.f3
Usage
Functions/Subroutines
subroutine dlapll (n, x, incx, y, incy, ssmin)
DLAPLL measures the linear dependence of two vectors.
Function/Subroutine Documentation
subroutine dlapll (integer n, double precision, dimension( * ) x, integer incx, double precision, dimension( * ) y, integer incy, double precision ssmin)
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
!> 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 Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Definition at line 101 of file dlapll.f.
Releases
4 releases since Debian 7 (Wheezy); the text changed 3 times.