SLAZQ4(3f)

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.