dlasq4(3)

NAME

DLASQ4 - compute an approximation TAU to the smallest

eigenvalue using values of d from the previous transform

SYNOPSIS

SUBROUTINE  DLASQ4(  I0,  N0,  Z,  PP,  N0IN, DMIN, DMIN1,
DMIN2, DN, DN1, DN2, TAU, TTYPE )
    INTEGER        I0, N0, N0IN, PP, TTYPE
    DOUBLE         PRECISION DMIN, DMIN1, DMIN2, DN,  DN1,
DN2, TAU
    DOUBLE         PRECISION Z( * )

PURPOSE

DLASQ4 computes an approximation TAU to the smallest

eigenvalue using values of d from the previous transform. I0

(input) INTEGER

First index.

N0 (input) INTEGER

Last index.

Z (input) DOUBLE PRECISION array, dimension ( 4*N )

Z holds the qd array.

PP (input) INTEGER

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

NOIN (input) INTEGER

The value of N0 at start of EIGTEST.

DMIN (input) DOUBLE PRECISION

Minimum value of d.

DMIN1 (input) DOUBLE PRECISION

Minimum value of d, excluding D( N0 ).

DMIN2 (input) DOUBLE PRECISION

Minimum value of d, excluding D( N0 ) and D( N0-1 ).

DN (input) DOUBLE PRECISION

d(N)

DN1 (input) DOUBLE PRECISION

d(N-1)

DN2 (input) DOUBLE PRECISION

d(N-2)

TAU (output) DOUBLE PRECISION

This is the shift.

TTYPE (output) INTEGER

Shift type.

FURTHER DETAILS

DLASQ4(3)