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

NAME

       LAPACK-3 - finds the square roots of the roots of the secular equation,

SYNOPSIS

       SUBROUTINE DLASD8( ICOMPQ, K, D, Z, VF, VL, DIFL, DIFR, LDDIFR, DSIGMA, WORK, INFO )

           INTEGER        ICOMPQ, INFO, K, LDDIFR

           DOUBLE         PRECISION  D(  * ), DIFL( * ), DIFR( LDDIFR, * ), DSIGMA( * ), VF( * ),
                          VL( * ), WORK( * ), Z( * )

PURPOSE

       DLASD8 finds the square roots of the roots of the secular equation,
        as defined by the values in DSIGMA and Z. It makes the appropriate
        calls to DLASD4, and stores, for each  element in D, the distance
        to its two nearest poles (elements in DSIGMA). It also updates
        the arrays VF and VL, the first and last components of all the
        right singular vectors of the original bidiagonal matrix.
        DLASD8 is called from DLASD6.

ARGUMENTS

        ICOMPQ  (input) INTEGER
                Specifies whether singular vectors are to be computed in
                factored form in the calling routine:
                = 0: Compute singular values only.
                = 1: Compute singular vectors in factored form as well.

        K       (input) INTEGER
                The number of terms in the rational function to be solved
                by DLASD4.  K >= 1.

        D       (output) DOUBLE PRECISION array, dimension ( K )
                On output, D contains the updated singular values.

        Z       (input/output) DOUBLE PRECISION array, dimension ( K )
                On entry, the first K elements of this array contain the
                components of the deflation-adjusted updating row vector.
                On exit, Z is updated.

        VF      (input/output) DOUBLE PRECISION array, dimension ( K )
                On entry, VF contains  information passed through DBEDE8.
                On exit, VF contains the first K components of the first
                components of all right singular vectors of the bidiagonal
                matrix.

        VL      (input/output) DOUBLE PRECISION array, dimension ( K )
                On entry, VL contains  information passed through DBEDE8.
                On exit, VL contains the first K components of the last
                components of all right singular vectors of the bidiagonal
                matrix.

        DIFL    (output) DOUBLE PRECISION array, dimension ( K )
                On exit, DIFL(I) = D(I) - DSIGMA(I).

        DIFR    (output) DOUBLE PRECISION array,
                dimension ( LDDIFR, 2 ) if ICOMPQ = 1 and
                dimension ( K ) if ICOMPQ = 0.
                On exit, DIFR(I,1) = D(I) - DSIGMA(I+1), DIFR(K,1) is not
                defined and will not be referenced.
                If ICOMPQ = 1, DIFR(1:K,2) is an array containing the
                normalizing factors for the right singular vector matrix.

        LDDIFR  (input) INTEGER
                The leading dimension of DIFR, must be at least K.

        DSIGMA  (input/output) DOUBLE PRECISION array, dimension ( K )
                On entry, the first K elements of this array contain the old
                roots of the deflated updating problem.  These are the poles
                of the secular equation.
                On exit, the elements of DSIGMA may be very slightly altered
                in value.

        WORK    (workspace) DOUBLE PRECISION array, dimension at least 3 * K

        INFO    (output) 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

FURTHER DETAILS

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

 LAPACK auxiliary routine (version 3.3.0)   April 2011                            DLASD8(3lapack)