MXNORM are ignored for scaling, where
          MXNORM is the maximum of the 1-norms of the original
          submatrices A(s,s) and B(s,s), with s = ILO:IHI.
          If THRESH &lt; 0, the subroutine finds the scaling factors
          for which some conditions, detailed below, are fulfilled.
          A sequence of increasing strictly positive threshold
          values is used.
          If THRESH = -1, the condition is that
             max( norm(A(s,s),1)/norm(B(s,s),1),
                  norm(B(s,s)