  if FACT = 'N' and the LAPACK Library routine ZGEES
                has failed to converge. This failure is not likely
                to occur. The matrix B will be unaltered but A will
                be destroyed.

</PRE>
<A name="Method"><B><FONT SIZE="+1">Method</FONT></B></A>
<PRE>
  The method used by the routine is based on the Bartels and Stewart
  method [1], except that it finds the upper triangular matrix U
  directly without first finding X and without the need to form the
  normal matrix op(B