GASP: PRESENT STATUS AND FUTURE PROSPECTS

Publisher Summary General-activity simulation program (GASP) is a simulation language that provides an organizational structure to build models that simulate the dynamic performance of systems on a digital computer. The organizational structure of GASP allows the variables that define system performance to be described by equations and logical conditions. System descriptions written in terms of difference or differential equations are referred to as continuous models. System descriptions written in terms of discrete changes based on logical conditions are referred to as discrete models. GASP supports the modeling of both continuous and discrete models and a combination of the two. The organizational structure of GASP specifies where and how system equations are written and the procedure for defining logical conditions that affect system variables. In GASP, an event approach is taken that specifies that discrete changes can only occur at event times. GASP can perform the time advancement functions required by a simulation model and call specific user-written routines to obtain system performance updates and system performance changes. GASP IV is used extensively for both discrete modeling, such as the study of inventory and queueing systems, and continuous modeling, such as car and aircraft dynamic analysis. GASP has been used to study steel making operations, electroplating procedures, the manufacturing of plastic tubing, and the production of corn syrup. Other areas where combined simulation is receiving attention is in crop planning and harvesting, environmental pollution analysis, ecological planning, transportation, computer and communication studies, and computer-aided manufacturing. GASP has also provided the basis for generalized network simulation languages and for a generalized crop simulation language.