rix C is also multiplied by the
  transformations, F = U'CZ, and the solution matrix Y of the
  transformed system

     Y + HYS' = F

  is computed by back substitution. Finally, the matrix Y is then
  multiplied by the orthogonal transformation matrices, X = UYZ', in
  order to obtain the solution matrix X to the original problem.

</PRE>
<A name="References"><B><FONT SIZE="+1">References</FONT></B></A>
<PRE>
  [1] Golub, G.H., Nash, S. and Van Loan, C.F.
      A Hessenberg-Schur method for the problem AX