GASP-V: Fortran Library for Modeling and Simulation of Mixed Continuous and Discrete Processes

Introduction

In those days, there existed no simulation language that would lend itself to a clean and complete description of such processes. First attempts to designing such a tool had been reported by Fahrland and Golden in the early seventies. However, these language designs had never been completed.

GASP-V is based on the software GASP-IV, a Fortran library for the simulation of discrete processes with continuous additions, a software that had been developed in the early seventies by Alan Pritsker of Purdue University.

GASP-IV was strong in its treatment of discrete processes (event descriptions, waiting queue models), but its capabilities for the simulation of continuous phenomena were limited. In particular, GASP-IV offered only one integration algorithm, a fixed-step Runge-Kutta method of fourth order, and also the algorithm it used for locating event times of state events, a bi-section method, was primitive and inefficient.

GASP-V enhanced the software by components that should allow an efficient simulation of discontinuous phenomena, as they e.g. occur in power-electronic switching circuits. Among other tools, several new integration algorithms were introduced as well as algorithms for the location in time of zero crossings of state change functions. GASP-V was successfully employed by a number of research groups in projects of theirs.

Historical Development

• In 1972, I began, on a grant by AGIE SA, to develop simulation models for electrical discharge machinary for die sinking work. The simulation of the plasma discharges led to numerical difficulties as the simulation software that I employed in those days, CSMP-III, was unable to handle the discontinuities correctly.

• For this reason, I decided in 1974 to develop a new software that should be specialized in simulating as accurately as possible heavily discontinuous models. This led to the development of GASP-V.

• GASP-V should become the kernel of my PhD dissertation that I completed in 1979.

Most Important Publications

1. Cellier, F.E. and A.E. Blitz (1976), GASP-V: A Universal Simulation Package, Proc. 8^th AICA Congress on Simulation of Systems, Delft, The Netherlands, pp.391-402.

2. Cellier, F.E., and P.J. Moebius (1979), Towards Robust General Purpose Simulation Software, Proc. ACM/SIGNUM Symposium on Numerical Ordinary Differential Equations, Urbana-Champaign, Illinois.

3. Cellier, F.E. (1979), Combined Continuous/Discrete System Simulation by Use of Digital Computers: Techniques and Tools, Swiss Federal Institute of Technology, ETH Zürich, Switzerland.

Sponsors

• ETH Zürich
• AGIE SA

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