Abstract
Two model reduction methods for discrete systems related to balanced realizations are described. The first is a technique which utilizes the least controllable and observable subsystem in deriving a balanced discrete reduced-order model that has some additional nice properties. For this techniques an L infinity norm bound on the reduction error is given. The second method is a new frequency weighting technique for discrete- and continuous-time systems where the input-normal or output-normal realizations are modified to include a simple frequency weighting. Also for this technique L infinity norm bounds on the weighted reduction errors are obtained.