Systems Analysis and Dynamic Simulation1)

Abstract The state–variable approach to systems analysis and dynamic simulation is based on the assumption that the state of each system at any moment may be quantitatively characterized and that changes in state may be described by mathematical equations. The basic distinction between state, rate and driving variables in this approach is illustrated by examples The conflict resulting from the large number of state variables that may be distinguished in any ecological system and the small number that can be handled in simulation models is treated and attention is given to the distinction between unique and recurring systems, especially with reference to the problem of model evaluation.