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zlapll.f(3) LAPACK zlapll.f(3)

NAME

zlapll.f -

SYNOPSIS

Functions/Subroutines


subroutine zlapll (N, X, INCX, Y, INCY, SSMIN)
 
ZLAPLL measures the linear dependence of two vectors.

Function/Subroutine Documentation

subroutine zlapll (integerN, complex*16, dimension( * )X, integerINCX, complex*16, dimension( * )Y, integerINCY, double precisionSSMIN)

ZLAPLL 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 COMPLEX*16 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 COMPLEX*16 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 101 of file zlapll.f.

Author

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