LAPLL - 5.2 English - 68552

LAPLL 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 – [in]

  N is INTEGER

  The length of the vectors X and Y.

• X – [inout]

  X is REAL array, dimension (1+(N-1)*INCX)

  On entry, X contains the N-vector X. On exit, X is overwritten.

• INCX – [in]

  INCX is INTEGER

  The increment between successive elements of X. INCX > 0.

• Y – [inout]

  Y is REAL array, dimension (1+(N-1)*INCY)

  On entry, Y contains the N-vector Y. On exit, Y is overwritten.

• INCY – [in]

  INCY is INTEGER

  The increment between successive elements of Y. INCY > 0.

• SSMIN – [out]

  SSMIN is REAL

  The smallest singular value of the N-by-2 matrix A = (X Y).