NAME

       lasq5 - lasq5: dqds step

SYNOPSIS

   Functions
       subroutine dlasq5 (i0, n0, z, pp, tau, sigma, dmin, dmin1, dmin2, dn, dnm1, dnm2, ieee,
           eps)
           DLASQ5 computes one dqds transform in ping-pong form. Used by sbdsqr and sstegr.
       subroutine slasq5 (i0, n0, z, pp, tau, sigma, dmin, dmin1, dmin2, dn, dnm1, dnm2, ieee,
           eps)
            SLASQ5 computes one dqds transform in ping-pong form. Used by sbdsqr and sstegr.

Detailed Description

Function Documentation

   subroutine dlasq5 (integer i0, integer n0, double precision, dimension( * ) z, integer pp,
       double precision tau, double precision sigma, double precision dmin, double precision
       dmin1, double precision dmin2, double precision dn, double precision dnm1, double
       precision dnm2, logical ieee, double precision eps)
       DLASQ5 computes one dqds transform in ping-pong form. Used by sbdsqr and sstegr.

       Purpose:

            DLASQ5 computes one dqds transform in ping-pong form, one
            version for IEEE machines another for non IEEE machines.

       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.

           TAU

                     TAU is DOUBLE PRECISION
                   This is the shift.

           SIGMA

                     SIGMA is DOUBLE PRECISION
                   This is the accumulated shift up to this step.

           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).

           IEEE

                     IEEE is LOGICAL
                   Flag for IEEE or non IEEE arithmetic.

           EPS

                     EPS is DOUBLE PRECISION
                   This is the value of epsilon used.

       Author
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

   subroutine slasq5 (integer i0, integer n0, real, dimension( * ) z, integer pp, real tau, real
       sigma, real dmin, real dmin1, real dmin2, real dn, real dnm1, real dnm2, logical ieee,
       real eps)
        SLASQ5 computes one dqds transform in ping-pong form. Used by sbdsqr and sstegr.

       Purpose:

            SLASQ5 computes one dqds transform in ping-pong form, one
            version for IEEE machines another for non IEEE machines.

       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.

           TAU

                     TAU is REAL
                   This is the shift.

           SIGMA

                     SIGMA is REAL
                   This is the accumulated shift up to this step.

           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).

           IEEE

                     IEEE is LOGICAL
                   Flag for IEEE or non IEEE arithmetic.

           EPS

                    EPS is REAL
                   This is the value of epsilon used.

       Author
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

Author

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