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

NAME

       DLAZQ3 - for deflation, computes a shift (TAU) and calls dqds

SYNOPSIS

       SUBROUTINE DLAZQ3( I0,  N0,  Z,  PP,  DMIN,  SIGMA,  DESIG, QMAX, NFAIL, ITER, NDIV, IEEE,
                          TTYPE, DMIN1, DMIN2, DN, DN1, DN2, TAU )

           LOGICAL        IEEE

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

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

           DOUBLE         PRECISION Z( * )

PURPOSE

       DLAZQ3 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) INTEGER
              Last index.

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

       PP     (input) INTEGER
              PP=0 for ping, PP=1 for pong.

       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.   TTYPE  is  passed  as an argument in order to save its value between
              calls to DLAZQ3

       DMIN1  (input/output) REAL
       DMIN2  (input/output) REAL
       DN     (input/output) REAL
       DN1    (input/output) REAL
       DN2    (input/output) REAL
       TAU    (input/output) REAL
              These are passed as arguments in order to save their values between calls to DLAZQ3

              This is a thread safe version of DLASQ3, which passes TTYPE, DMIN1, DMIN2, DN, DN1.
              DN2  and  TAU  through  the  argument  list  in  place  of declaring them in a SAVE
              statment.

 LAPACK auxiliary routine (version 3.1)    October 2006                           DLAZQ3(3lapack)