dlasq4 (l) - Linux Manuals

dlasq4: computes an approximation TAU to the smallest eigenvalue using values of d from the previous transform

NAME

DLASQ4 - computes 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, G )

    

INTEGER I0, N0, N0IN, PP, TTYPE

    

DOUBLE PRECISION DMIN, DMIN1, DMIN2, DN, DN1, DN2, G, 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.
G (input/output) REAL

G is passed as an argument in order to save its value between
calls to DLASQ4.

FURTHER DETAILS