DLASQ4  -  compute  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.

             Shift type.


FURTHER DETAILS



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