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dlapll.f(3) LAPACK dlapll.f(3)

NAME

dlapll.f

SYNOPSIS

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.

Date:

December 2016

Definition at line 104 of file dlapll.f.

Author

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Tue Nov 14 2017 Version 3.8.0