On model reduction by modified Cauer form

A simple algorithm for obtaining the continued fraction quotients in the modified Cauer form (MCF) from the given system matrices in companion form is presented. In the sequel, the triple of all lower order models in companion form is directly obtained. A matrix method of obtaining the time-moments and Markov parameters from the MCF quotients is also outlined. Finally, it is shown that system reduction by matching a set of MCF quotients is equivalent to system reduction by matching a set of time-moments and Markov parameters.