Rational approximation theory and its applications in systems engineering: an overview

This article offers an overview of rational approximation theory and its applications in systems engineering. The importance of rational approximation theory in systems engineering and signal processing can be easily understood from the observation that all the transfer functions (matrices) of linear time-invariant systems and digital filters are rational functions (matrices). Rational approximation has a long history in the field of approximation theory, an important and active branch of mathematics, and has found very broad applications in control and systems engineering.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>