ABSTRACT
Two approaches for finding reduced order models for linear delay-differential type systems are described. The first is a balanced approximation approach based on generalized reachability and observability gramians. The second is based on frequency response data in which a rational function (that is, low pass or band pass filter) approximation is sought with a good match to the frequency response data. The second approach is exploited as a way to find root chains of exponential polynomials, that is, roots of the characteristic function of the linear delay-differential type systems.
