slazq4(l) - Linux man page

Name

SLAZQ4 - an approximation TAU to the smallest eigenvalue using values of d from the previous transform

Synopsis

SUBROUTINE SLAZQ4(

I0, N0, Z, PP, N0IN, DMIN, DMIN1, DMIN2, DN, DN1, DN2, TAU, TTYPE, G )

INTEGER

I0, N0, N0IN, PP, TTYPE

REAL

DMIN, DMIN1, DMIN2, DN, DN1, DN2, G, TAU

REAL

Z( * )

Purpose

SLAZQ4 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) REAL array, dimension ( 4*N )
Z holds the qd array.

PP (input) INTEGER
PP=0 for ping, PP=1 for pong.

N0IN (input) INTEGER
The value of N0 at start of EIGTEST.

DMIN (input) REAL
Minimum value of d.

DMIN1 (input) REAL
Minimum value of d, excluding D( N0 ).

DMIN2 (input) REAL
Minimum value of d, excluding D( N0 ) and D( N0-1 ).

DN (input) REAL
d(N)

DN1 (input) REAL
d(N-1)

DN2 (input) REAL
d(N-2)

TAU (output) REAL
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 SLAZQ4

Further Details

This is a thread safe version of SLASQ4, which passes G through the argument list in place of declaring G in a SAVE statment.