FREQUENCY-RESPONSE COMPUTATION VIA RATIONAL INTERPOLATION

A simple rational interpolation method is given for estimating a frequ ency response matrix. The method is based on a generalization of the r esolvent identity that avoids the potential inaccuracies introduced by the subtraction of nearly equal values in the calculation of the diff erence terms. When coupled with a pole cancellation method, the result ing interpolation algorithm is accurate and efficient. Somewhat surpri singly, the error in this procedure has the form of a modified respons e matrix, which means that the interpolation algorithm can be used to approximate both the response matrix and the error.