© 1986 by Institute of Mathematics and its Applications
Balanced, Normal, and Intermediate Realizations of Nonrational Transfer Functions
Department of Mathematics, University of Glasgow Scotland
For a very general transfer-function matrix G(z) we construct a one-parameter family (A
, B
, C
) of state-space realizations of G(z), continuously indexed by
(0, 1), such that the realizations corresponding to
equal to 0,
, and 1 are output-normal, balanced, and input-normal respectively. The realization with parameter
has the property that M1
= W
, where M and W are the observability and controllability gramians of the system respectively. (A
, B
, C
) has bounded reachability and observability operators and ||Aalpha;||
1. The class of admissible G(z) contains all matrix functions bounded and analytic in the complement of the closed unit disc and vanishing at infinity, and also contains some unbounded functions.