ABSTRACT
Computer simulation of a system described by differential equations requires that some element of the system be approximated by discrete quantities. There are two system aspects that can be made discrete: time and state. When time is discrete, the differential equation is approximated by a difference equation (i.e., a discrete-time system), and the solution is calculated at fixed points in time. When the state is discrete, the differential equation is approximated by a discrete-event system. Events correspond to jumps through the discrete state space of the approximation.
