  during the computation of the solution matrix X.
                That is, the estimated reciprocal condition number
                of T is less than or equal to TOL.

</PRE>
<A name="Method"><B><FONT SIZE="+1">Method</FONT></B></A>
<PRE>
  Matrices A and B are assumed to be in (upper or lower) Hessenberg
  or Schur form (with at least one of them in Schur form). The
  solution matrix X is then computed by rows or columns via the back
  substitution scheme proposed by Golub, Nash and Van Loan (see
  [1]),