SRC/dlasq6.f(3)

NAME
SRC/dlasq6.f

SYNOPSIS

  Functions/Subroutines
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.

Function/Subroutine 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.

Definition at line 117 of file dlasq6.f.

Author

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