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 (integerN, double precision, dimension( * )X, integerINCX, double precision, dimension( * )Y, integerINCY, double precisionSSMIN)

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:
    September 2012

Definition at line 103 of file dlapll.f.

Author

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