><FONT SIZE="+1">Purpose</FONT></B>
<PRE>
  To estimate the conditioning and compute an error bound on the
  solution of the real discrete-time matrix algebraic Riccati
  equation (see FURTHER COMMENTS)
                              -1
      X = op(A)'*X*(I_n + G*X)  *op(A) + Q,                      (1)

  where op(A) = A or A' (A**T) and Q, G are symmetric (Q = Q**T,
  G = G**T). The matrices A, Q and G are N-by-N and the solution X
  is N-by-N.

</PRE>
<A name="Specification"><B><FONT SIZE="+1">Specificat