NAME

       dlasd0.f -

SYNOPSIS

   Functions/Subroutines
       subroutine dlasd0 (N, SQRE, D, E, U, LDU, VT, LDVT, SMLSIZ, IWORK, WORK, INFO)
           DLASD0 computes the singular values of a real upper bidiagonal n-by-m matrix B with
           diagonal d and off-diagonal e. Used by sbdsdc.

Function/Subroutine Documentation

   subroutine dlasd0 (integerN, integerSQRE, double precision, dimension( * )D, double precision,
       dimension( * )E, double precision, dimension( ldu, * )U, integerLDU, double precision,
       dimension( ldvt, * )VT, integerLDVT, integerSMLSIZ, integer, dimension( * )IWORK, double
       precision, dimension( * )WORK, integerINFO)
       DLASD0 computes the singular values of a real upper bidiagonal n-by-m matrix B with
       diagonal d and off-diagonal e. Used by sbdsdc.

       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.

       Parameters:
           N

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

           SQRE

                     SQRE is 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

                     D is 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

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

           U

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

           LDU

                     LDU is INTEGER
                    On entry, leading dimension of U.

           VT

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

           LDVT

                     LDVT is INTEGER
                    On entry, leading dimension of VT.

           SMLSIZ

                     SMLSIZ is INTEGER
                    On entry, maximum size of the subproblems at the
                    bottom of the computation tree.

           IWORK

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

           WORK

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

           INFO

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

       Author:
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

       Date:
           September 2012

       Contributors:
           Ming Gu and Huan Ren, Computer Science Division, University of California at Berkeley,
           USA

       Definition at line 152 of file dlasd0.f.

Author

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