Dw ) ,
             ( 0   Aw  )          (  Bw  )

        Ao = (  A   0  ) ,   Co = ( Dv*C  Cv ) .
             ( Bv*C Av )

  Consider the partitioned Grammians

        Pi = ( P11  P12 )   and    Qo = ( Q11  Q12 ) ,
             ( P12' P22 )               ( Q12' Q22 )

  where P11 and Q11 are the leading N-by-N parts of Pi and Qo,
  respectively, and let P0 and Q0 be non-negative definite matrices
  defined in the combination method [4]
                                     -1
         P0 = P11 - ALPHAC**