Provided by: liblapack-doc_3.3.1-1_all bug

NAME

       LAPACK-3 - is called from SGESVJ as a pre-processor and that is its main purpose

SYNOPSIS

       SUBROUTINE SGSVJ0( JOBV,  M, N, A, LDA, D, SVA, MV, V, LDV, EPS, SFMIN, TOL, NSWEEP, WORK,
                          LWORK, INFO )

           IMPLICIT       NONE

           INTEGER        INFO, LDA, LDV, LWORK, M, MV, N, NSWEEP

           REAL           EPS, SFMIN, TOL

           CHARACTER*1    JOBV

           REAL           A( LDA, * ), SVA( N ), D( N ), V( LDV, * ), WORK( LWORK )

PURPOSE

       SGSVJ0 is called from SGESVJ as a pre-processor and that is its main purpose.  It  applies
       Jacobi rotations in the same way as SGESVJ does, but
        it does not check convergence (stopping criterion). Few tuning
        parameters (marked by [TP]) are available for the implementer.
        Further Details
        SGSVJ0 is used just to enable SGESVJ to call a simplified version of
        itself to work on a submatrix of the original matrix.
        Contributors
        ~~~~~~~~~~~~
        Zlatko Drmac (Zagreb, Croatia) and Kresimir Veselic (Hagen, Germany)
        Bugs, Examples and Comments
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~
        Please report all bugs and send interesting test examples and comments to
        drmac@math.hr. Thank you.

ARGUMENTS

        JOBV    (input) CHARACTER*1
                Specifies whether the output from this procedure is used
                to compute the matrix V:
                = 'V': the product of the Jacobi rotations is accumulated
                by postmulyiplying the N-by-N array V.
                (See the description of V.)
                = 'A': the product of the Jacobi rotations is accumulated
                by postmulyiplying the MV-by-N array V.
                (See the descriptions of MV and V.)
                = 'N': the Jacobi rotations are not accumulated.

        M       (input) INTEGER
                The number of rows of the input matrix A.  M >= 0.

        N       (input) INTEGER
                The number of columns of the input matrix A.
                M >= N >= 0.

        A       (input/output) REAL array, dimension (LDA,N)
                On entry, M-by-N matrix A, such that A*diag(D) represents
                the input matrix.
                On exit,
                A_onexit * D_onexit represents the input matrix A*diag(D)
                post-multiplied by a sequence of Jacobi rotations, where the
                rotation threshold and the total number of sweeps are given in
                TOL and NSWEEP, respectively.
                (See the descriptions of D, TOL and NSWEEP.)

        LDA     (input) INTEGER
                The leading dimension of the array A.  LDA >= max(1,M).

        D       (input/workspace/output) REAL array, dimension (N)
                The array D accumulates the scaling factors from the fast scaled
                Jacobi rotations.
                On entry, A*diag(D) represents the input matrix.
                On exit, A_onexit*diag(D_onexit) represents the input matrix
                post-multiplied by a sequence of Jacobi rotations, where the
                rotation threshold and the total number of sweeps are given in
                TOL and NSWEEP, respectively.
                (See the descriptions of A, TOL and NSWEEP.)

        SVA     (input/workspace/output) REAL array, dimension (N)
                On entry, SVA contains the Euclidean norms of the columns of
                the matrix A*diag(D).
                On exit, SVA contains the Euclidean norms of the columns of
                the matrix onexit*diag(D_onexit).

        MV      (input) INTEGER
                If JOBV .EQ. 'A', then MV rows of V are post-multipled by a
                sequence of Jacobi rotations.
                If JOBV = 'N',   then MV is not referenced.

        V       (input/output) REAL array, dimension (LDV,N)
                If JOBV .EQ. 'V' then N rows of V are post-multipled by a
                sequence of Jacobi rotations.
                If JOBV .EQ. 'A' then MV rows of V are post-multipled by a
                sequence of Jacobi rotations.
                If JOBV = 'N',   then V is not referenced.

        LDV     (input) INTEGER
                The leading dimension of the array V,  LDV >= 1.
                If JOBV = 'V', LDV .GE. N.
                If JOBV = 'A', LDV .GE. MV.

        EPS     (input) INTEGER
                EPS = SLAMCH('Epsilon')

        SFMIN   (input) INTEGER
                SFMIN = SLAMCH('Safe Minimum')

        TOL     (input) REAL
                TOL is the threshold for Jacobi rotations. For a pair
                A(:,p), A(:,q) of pivot columns, the Jacobi rotation is
                applied only if ABS(COS(angle(A(:,p),A(:,q)))) .GT. TOL.

        NSWEEP  (input) INTEGER
                NSWEEP is the number of sweeps of Jacobi rotations to be
                performed.

        WORK    (workspace) REAL array, dimension LWORK.

        LWORK   (input) INTEGER
                LWORK is the dimension of WORK. LWORK .GE. M.

        INFO    (output) INTEGER
                = 0 : successful exit.
                < 0 : if INFO = -i, then the i-th argument had an illegal value

 LAPACK routine (version 3.3.1)             April 2011                            SGSVJ0(3lapack)