2*P12*P22 *P21 ,
                                     -1
         Q0 = Q11 - ALPHAO**2*Q12*Q22 *Q21.

  The frequency-weighted controllability and observability
  Grammians, P and Q, respectively, are defined as follows:
  P = P0 if JOBC = 'S' (standard combination method [4]);
  P = P1 &gt;= P0 if JOBC = 'E', where P1 is the controllability
  Grammian defined to enforce stability for a modified combination
  method of [4];
  Q = Q0 if JOBO = 'S' (standard combination method [4]);
  Q = Q1 &gt;= Q0 if JOBO 