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dlasd0 examples
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Man Page Details
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NAME
       DLASD0  -  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 com-
       putes orthogonal matrices U and VT such that B = U * S * VT. The singu-
       lar values S are overwritten on D.

       A  related  subroutine,  DLASDA, computes only the singular values, and
       optionally, the singular 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  (workspace) INTEGER work array.
              Dimension must be at least (8 * N)

       WORK   (workspace) 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

