clapll.f File Reference

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Functions/Subroutines
subroutine	clapll (N, X, INCX, Y, INCY, SSMIN)
	CLAPLL

Function/Subroutine Documentation

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

CLAPLL

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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 COMPLEX 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 COMPLEX 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

November 2011

Definition at line 101 of file clapll.f.

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