s determined.
  If [Y1'|Y2']' is a basis for Ys, then the required solution is
                    -1
         X = Y2 x Y1  .

</PRE>
<A name="References"><B><FONT SIZE="+1">References</FONT></B></A>
<PRE>
  [1] Van Dooren, P.
      A Generalized Eigenvalue Approach for Solving Riccati
      Equations.
      SIAM J. Sci. Stat. Comp., 2, pp. 121-135, 1981.

  [2] Arnold, III, W.F. and Laub, A.J.
      Generalized Eigenproblem Algorithms and Software for
      Algebraic Riccati Equations.
      Proc. IEEE, 72