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DLASD0(1) LAPACK auxiliary routine (version 3.2) DLASD0(1)

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

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 singular vectors in compact form.

ARGUMENTS

On entry, the row dimension of the upper bidiagonal matrix. This is also the dimension of the main diagonal array D.
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;
On entry D contains the main diagonal of the bidiagonal matrix. On exit D, if INFO = 0, contains its singular values.
Contains the subdiagonal entries of the bidiagonal matrix. On exit, E has been destroyed.
On exit, U contains the left singular vectors.
On entry, leading dimension of U.
On exit, VT' contains the right singular vectors.
On entry, leading dimension of VT. SMLSIZ (input) INTEGER On entry, maximum size of the subproblems at the bottom of the computation tree.
Dimension must be at least (8 * N)
Dimension must be at least (3 * M**2 + 2 * M)
= 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

November 2008 LAPACK auxiliary routine (version 3.2)