NAME

       lasq6 - lasq6: dqds step

SYNOPSIS

   Functions
       subroutine dlasq6 (i0, n0, z, pp, dmin, dmin1, dmin2, dn, dnm1, dnm2)
           DLASQ6 computes one dqd transform in ping-pong form. Used by sbdsqr and sstegr.
       subroutine slasq6 (i0, n0, z, pp, dmin, dmin1, dmin2, dn, dnm1, dnm2)
           SLASQ6 computes one dqd transform in ping-pong form. Used by sbdsqr and sstegr.

Detailed Description

Function Documentation

   subroutine dlasq6 (integer i0, integer n0, double precision, dimension( * ) z, integer pp,
       double precision dmin, double precision dmin1, double precision dmin2, double precision
       dn, double precision dnm1, double precision dnm2)
       DLASQ6 computes one dqd transform in ping-pong form. Used by sbdsqr and sstegr.

       Purpose:

            DLASQ6 computes one dqd (shift equal to zero) transform in
            ping-pong form, with protection against underflow and overflow.

       Parameters
           I0

                     I0 is INTEGER
                   First index.

           N0

                     N0 is INTEGER
                   Last index.

           Z

                     Z is DOUBLE PRECISION array, dimension ( 4*N )
                   Z holds the qd array. EMIN is stored in Z(4*N0) to avoid
                   an extra argument.

           PP

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

           DMIN

                     DMIN is DOUBLE PRECISION
                   Minimum value of d.

           DMIN1

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

           DMIN2

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

           DN

                     DN is DOUBLE PRECISION
                   d(N0), the last value of d.

           DNM1

                     DNM1 is DOUBLE PRECISION
                   d(N0-1).

           DNM2

                     DNM2 is DOUBLE PRECISION
                   d(N0-2).

       Author
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

   subroutine slasq6 (integer i0, integer n0, real, dimension( * ) z, integer pp, real dmin, real
       dmin1, real dmin2, real dn, real dnm1, real dnm2)
       SLASQ6 computes one dqd transform in ping-pong form. Used by sbdsqr and sstegr.

       Purpose:

            SLASQ6 computes one dqd (shift equal to zero) transform in
            ping-pong form, with protection against underflow and overflow.

       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. EMIN is stored in Z(4*N0) to avoid
                   an extra argument.

           PP

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

           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(N0), the last value of d.

           DNM1

                     DNM1 is REAL
                   d(N0-1).

           DNM2

                     DNM2 is REAL
                   d(N0-2).

       Author
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

Author

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