LAPACK  3.5.0
LAPACK: Linear Algebra PACKage
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slapll.f File Reference

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Functions/Subroutines

subroutine slapll (N, X, INCX, Y, INCY, SSMIN)
 SLAPLL measures the linear dependence of two vectors. More...
 

Function/Subroutine Documentation

subroutine slapll ( integer  N,
real, dimension( * )  X,
integer  INCX,
real, dimension( * )  Y,
integer  INCY,
real  SSMIN 
)

SLAPLL measures the linear dependence of two vectors.

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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
[in]N
          N is INTEGER
          The length of the vectors X and Y.
[in,out]X
          X is REAL array,
                         dimension (1+(N-1)*INCX)
          On entry, X contains the N-vector X.
          On exit, X is overwritten.
[in]INCX
          INCX is INTEGER
          The increment between successive elements of X. INCX > 0.
[in,out]Y
          Y is REAL array,
                         dimension (1+(N-1)*INCY)
          On entry, Y contains the N-vector Y.
          On exit, Y is overwritten.
[in]INCY
          INCY is INTEGER
          The increment between successive elements of Y. INCY > 0.
[out]SSMIN
          SSMIN is REAL
          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 slapll.f.

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