NAME

       slasq4.f -

SYNOPSIS

   Functions/Subroutines
       subroutine slasq4 (I0, N0, Z, PP, N0IN, DMIN, DMIN1, DMIN2, DN, DN1, DN2, TAU, TTYPE, G)
           SLASQ4 computes an approximation to the smallest eigenvalue using values of d from the
           previous transform. Used by sbdsqr.

Function/Subroutine Documentation

   subroutine slasq4 (integer I0, integer N0, real, dimension( * ) Z, integer PP, integer N0IN,
       real DMIN, real DMIN1, real DMIN2, real DN, real DN1, real DN2, real TAU, integer TTYPE,
       real G)
       SLASQ4 computes an approximation to the smallest eigenvalue using values of d from the
       previous transform. Used by sbdsqr.

       Purpose:

            SLASQ4 computes an approximation TAU to the smallest eigenvalue
            using values of d from the previous transform.

       Parameters:
           I0

                     I0 is INTEGER
                   First index.

           N0

                     N0 is INTEGER
                   Last index.

           Z

                     Z is REAL array, dimension ( 4*N )
                   Z holds the qd array.

           PP

                     PP is INTEGER
                   PP=0 for ping, PP=1 for pong.

           N0IN

                     N0IN is INTEGER
                   The value of N0 at start of EIGTEST.

           DMIN

                     DMIN is REAL
                   Minimum value of d.

           DMIN1

                     DMIN1 is REAL
                   Minimum value of d, excluding D( N0 ).

           DMIN2

                     DMIN2 is REAL
                   Minimum value of d, excluding D( N0 ) and D( N0-1 ).

           DN

                     DN is REAL
                   d(N)

           DN1

                     DN1 is REAL
                   d(N-1)

           DN2

                     DN2 is REAL
                   d(N-2)

           TAU

                     TAU is REAL
                   This is the shift.

           TTYPE

                     TTYPE is INTEGER
                   Shift type.

           G

                     G is REAL
                   G is passed as an argument in order to save its value between
                   calls to SLASQ4.

       Author:
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

       Date:
           September 2012

       Further Details:

             CNST1 = 9/16

Author

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