ABSTRACT
Dynamic modeling based on functions has a different emphasis than the dynamic modeling based on states or events discussed in Chapter 7. In general, functions describe a mapping or conversion from one set of variables to another set of variables in the target system. Typically, the functions form an interconnected network that describes the dynamic processes of the target system. For each function, the mapping is from input variables to output variables. However, in the network of functions the outputs from some functions may serve as the inputs for subsequent functions. Therefore, the network as a whole may have functions representing early, middle, or late sets of events and processes in the target system. Some modeling texts explicitly cover this form of modeling (e.g. Morrison, 1991, and Fishwick, 1995), and some computer modeling languages are explicitly designed to facilitate functional modeling (e.g. Franta, 1977).
