Authors\´ Reply [to "Corrections and Comments to \´Model Reduction of Discrete Linear Systems Via Frequency-Domain Balanced Structure\´"]

For original paper, see N. L. Prajapathy et al., ibid, vol. 54, no. 3, pp. 682-683, (2007). Reply to the comments on model reduction technique for discrete linear time invariant systems are presented. The proposed technique is based on a conceptual view point of the controllability and observability Grammians balancing of a system in an arbitrary frequency range. It can be considered as the generalization of the Moore´s (1981) balance structure approach in a specific frequency range of operation. Two modified Lyapunov equations are derived for the proposed frequency domain balancing. The transfer function of the sixth-order Cheby-shev type 1 filter is considered. The Nyquist plots for the original filter as well as the reduced-order filters based on the Moore´s balanced technique and the proposed method.