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

NAME

       LAPACK-3 - checks for deflation, computes a shift (TAU) and calls dqds

SYNOPSIS

       SUBROUTINE DLASQ3( I0,  N0,  Z,  PP,  DMIN,  SIGMA,  DESIG, QMAX, NFAIL, ITER, NDIV, IEEE,
                          TTYPE, DMIN1, DMIN2, DN, DN1, DN2, G, TAU )

           LOGICAL        IEEE

           INTEGER        I0, ITER, N0, NDIV, NFAIL, PP

           DOUBLE         PRECISION DESIG, DMIN, DMIN1, DMIN2, DN, DN1, DN2, G, QMAX, SIGMA, TAU

           DOUBLE         PRECISION Z( * )

PURPOSE

       DLASQ3 checks for deflation, computes a shift (TAU) and calls dqds.
        In case of failure it changes shifts, and tries again until output
        is positive.

ARGUMENTS

        I0     (input) INTEGER
               First index.

        N0     (input/output) INTEGER
               Last index.

        Z      (input) DOUBLE PRECISION array, dimension ( 4*N )
               Z holds the qd array.

        PP     (input/output) INTEGER
               PP=0 for ping, PP=1 for pong.
               PP=2 indicates that flipping was applied to the Z array
               and that the initial tests for deflation should not be
               performed.

        DMIN   (output) DOUBLE PRECISION
               Minimum value of d.

        SIGMA  (output) DOUBLE PRECISION
               Sum of shifts used in current segment.

        DESIG  (input/output) DOUBLE PRECISION
               Lower order part of SIGMA

        QMAX   (input) DOUBLE PRECISION
               Maximum value of q.

        NFAIL  (output) INTEGER
               Number of times shift was too big.

        ITER   (output) INTEGER
               Number of iterations.

        NDIV   (output) INTEGER
               Number of divisions.

        IEEE   (input) LOGICAL
               Flag for IEEE or non IEEE arithmetic (passed to DLASQ5).

        TTYPE  (input/output) INTEGER
               Shift type.

        DMIN1  (input/output) DOUBLE PRECISION

        DMIN2  (input/output) DOUBLE PRECISION

        DN     (input/output) DOUBLE PRECISION

        DN1    (input/output) DOUBLE PRECISION

        DN2    (input/output) DOUBLE PRECISION

        G      (input/output) DOUBLE PRECISION

        TAU    (input/output) DOUBLE PRECISION
               These are passed as arguments in order to save their values
               between calls to DLASQ3.

 LAPACK routine (version 3.2.2)             April 2011                            DLASQ3(3lapack)