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RedHat 9 (Linux i386) - man page for dlasd0 (redhat section l)

DLASD0(l)					)					DLASD0(l)

NAME
       DLASD0  -  a divide and conquer approach, DLASD0 computes the singular value decomposition
       (SVD) of a real upper bidiagonal N-by-M matrix B with diagonal D and offdiagonal E,  where
       M = N + SQRE

SYNOPSIS
       SUBROUTINE DLASD0( N, SQRE, D, E, U, LDU, VT, LDVT, SMLSIZ, IWORK, WORK, INFO )

	   INTEGER	  INFO, LDU, LDVT, N, SMLSIZ, SQRE

	   INTEGER	  IWORK( * )

	   DOUBLE	  PRECISION D( * ), E( * ), U( LDU, * ), VT( LDVT, * ), WORK( * )

PURPOSE
       Using  a  divide  and  conquer  approach, DLASD0 computes the singular value decomposition
       (SVD) of a real upper bidiagonal N-by-M matrix B with diagonal D and offdiagonal E,  where
       M  =  N	+ SQRE. The algorithm computes orthogonal matrices U and VT such that B = U * S *
       VT. The singular values S are overwritten on D.

       A related subroutine, DLASDA, computes only the singular values, and optionally, the  sin-
       gular vectors in compact form.

ARGUMENTS
       N      (input) INTEGER
	      On  entry,  the  row  dimension  of  the upper bidiagonal matrix.  This is also the
	      dimension of the main diagonal array D.

       SQRE   (input) INTEGER
	      Specifies the column dimension of the  bidiagonal  matrix.   =  0:  The  bidiagonal
	      matrix has column dimension M = N;
	      = 1: The bidiagonal matrix has column dimension M = N+1;

       D      (input/output) DOUBLE PRECISION array, dimension (N)
	      On entry D contains the main diagonal of the bidiagonal matrix.  On exit D, if INFO
	      = 0, contains its singular values.

       E      (input) DOUBLE PRECISION array, dimension (M-1)
	      Contains the subdiagonal entries of the bidiagonal matrix.  On  exit,  E	has  been
	      destroyed.

       U      (output) DOUBLE PRECISION array, dimension at least (LDQ, N)
	      On exit, U contains the left singular vectors.

       LDU    (input) INTEGER
	      On entry, leading dimension of U.

       VT     (output) DOUBLE PRECISION array, dimension at least (LDVT, M)
	      On exit, VT' contains the right singular vectors.

       LDVT   (input) INTEGER
	      On entry, leading dimension of VT.

	      SMLSIZ  (input)  INTEGER On entry, maximum size of the subproblems at the bottom of
	      the computation tree.

       IWORK  INTEGER work array.
	      Dimension must be at least (8 * N)

       WORK   DOUBLE PRECISION work array.
	      Dimension must be at least (3 * M**2 + 2 * M)

       INFO   (output) INTEGER
	      = 0:  successful exit.
	      < 0:  if INFO = -i, the i-th argument had an illegal value.
	      > 0:  if INFO = 1, an singular value did not converge

FURTHER DETAILS
       Based on contributions by
	  Ming Gu and Huan Ren, Computer Science Division, University of
	  California at Berkeley, USA

LAPACK version 3.0			   15 June 2000 				DLASD0(l)


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