Multifrequency Pade approximation via Jordan continued-fraction expansion

The multifrequency Pade approximation of transfer functions is performed via the Jordan-type continued-fraction expansion. An efficient algorithm that requires no complex algebra is derived for expanding a transfer function into a Jordan continued fraction about arbitrary points s=±jω_j on the imaginary axis of the s-plane. Also derived is a forward inversion algorithm for inverting a multifrequency Jordan continued-fraction expansion into a rational form. The algorithms presented are amenable for obtaining a family of frequency-response matched models of different orders for a high-order transfer function via a single set of computations