SRC/slasq5.f(3)

NAME
SRC/slasq5.f

SYNOPSIS

  Functions/Subroutines
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.

Function/Subroutine Documentation

  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.

Definition at line 142 of file slasq5.f.

Author

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