LAPACK
3.4.2
LAPACK: Linear Algebra PACKage

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Functions/Subroutines  
subroutine  dlapll (N, X, INCX, Y, INCY, SSMIN) 
DLAPLL measures the linear dependence of two vectors. 
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.
Download DLAPLL + dependencies [TGZ] [ZIP] [TXT]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 2by2 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.
[in]  N  N is INTEGER The length of the vectors X and Y. 
[in,out]  X  X is DOUBLE PRECISION array, dimension (1+(N1)*INCX) On entry, X contains the Nvector 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 DOUBLE PRECISION array, dimension (1+(N1)*INCY) On entry, Y contains the Nvector Y. On exit, Y is overwritten. 
[in]  INCY  INCY is INTEGER The increment between successive elements of Y. INCY > 0. 
[out]  SSMIN  SSMIN is DOUBLE PRECISION The smallest singular value of the Nby2 matrix A = ( X Y ). 
Definition at line 103 of file dlapll.f.