A Jordan-type CFE for multipoint Pade approximants

A Jordan-type continued fraction expansion (CFE) is used to produce multipoint Pade approximants of high-order plant. An efficient algorithm which is conceptually simple and computationally convenient is proposed for expanding a transfer function into a Jordan continued fraction about any points of interest s=±jω_i on the imaginary axis of the s-plane. No tedious computations involving complex algebra are required. This technique overcomes the chief problem of the Pade class, namely, that unstable estimates may result for a stable system. Also presented is an algorithm for inverting the multipoint Jordan continued fraction into a rational form. Finally, an example is used to illustrate the application of the proposed method