THE EXTENDED GENERALIZED DISTANCE PROBLEM IN DISCRETE-TIME

We obtain the class of all solutions to the extended (two block) gener alized distance problem for discrete-time systems by employing the so- called 'signature condition'-a generalized Popov theory type argument which parallels the J-spectral factorization approach. The novelty is that we derive explicit state-space formulae in terms of one Riccati a nd one Lyapunov equation while we remove the usual assumption in the d iscrete case on the time reversibility (invertibility of the state mat rix) of the system to be approximated. (C) 1998 John Wiley & Sons, Ltd .