SRC/dlasq5.f(3)

NAME
SRC/dlasq5.f

SYNOPSIS

  Functions/Subroutines
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.

Function/Subroutine 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.

Definition at line 142 of file dlasq5.f.

Author

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