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dlasq4 examples
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Man Page Details
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NAME
       DLASQ4  -  an approximation TAU to the smallest eigenvalue using values
       of d from the previous transform

SYNOPSIS
       SUBROUTINE DLASQ4( I0, N0, Z, PP, N0IN, DMIN, DMIN1,  DMIN2,  DN,  DN1,
                          DN2, TAU, TTYPE )

           INTEGER        I0, N0, N0IN, PP, TTYPE

           DOUBLE         PRECISION DMIN, DMIN1, DMIN2, DN, DN1, DN2, TAU

           DOUBLE         PRECISION Z( * )

  Purpose
  =======

  DLASQ4 computes an approximation TAU to the smallest eigenvalue 
  using values of d from the previous transform.

  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.

  NOIN  (input) INTEGER
        The value of N0 at start of EIGTEST.

  DMIN  (input) DOUBLE PRECISION
        Minimum value of d.

  DMIN1 (input) DOUBLE PRECISION
        Minimum value of d, excluding D( N0 ).

  DMIN2 (input) DOUBLE PRECISION
        Minimum value of d, excluding D( N0 ) and D( N0-1 ).

  DN    (input) DOUBLE PRECISION
        d(N)

  DN1   (input) DOUBLE PRECISION
        d(N-1)

  DN2   (input) DOUBLE PRECISION
        d(N-2)

  TAU   (output) DOUBLE PRECISION
        This is the shift.

  TTYPE (output) INTEGER
        Shift type.

  Further Details
  ===============
  CNST1 = 9/16

