ABSTRACT
An integral part of systems science and engineering is that of modeling. By observing certain phenomena, the immediate task consists of two parts: we wish to describe it and then determine its subsequent behavior. It is well known, in many important cases, that a useful and convenient representation of the system state is by means of a finite-dimensional vector at a particular instant of time. This constitutes a state-space modeling via ordinary differential equations, which has formed a great deal of the literature on dynamical systems. On another dimension, due to increasing complexity and interconnection of many physical systems to suit growing demand, other factors have seemingly been taken into account in the process of modeling. One important factor is that the rate of change of several physical systems depends not only on their present state, but also in their past history or delayed information among system components.
