Easy ModelWorks

An Interactive Modeling and Simulation Environment for Personal Computers

What Is Easy ModelWorks?   Features   Formal Interface   Availability   Author   References

1 - What Is Easy ModelWorks?

Easy ModelWorks is an interactive modelling and simulation environment for beginners. It is the small sister of ModelWorks (Fischlin 1991 , Fischlin et al. 1994 ) but is much easier to learn. In fact it is based on a full-fledged ModelWorks, but allows only to model either one continuous-time differential equation (DESS) or one discrete-time difference equation (SQM) system specifications at a time.

The system specifications are made in ordinary mathematical notation and can be modified any time. Model parameters, simulation time, integration methos, monitoring (table, graphics) can be controlled easily at run time. You may even click into a state space display and define graphically initial conditions. This allows to explore directly the stability behavior of 2-dimensional systems and to draw easily the phase portrait of such dynamic systems.

Easy ModelWorks models can be saved to disk anytime. There they are stored as simple text files. Easy ModelWorks models can also be written with any word processor or text editor. These text files are written in the so-called EMWSL (Easy ModelWorks Simulation Language). You may anytime translate an Easy ModelWorks model into a ModelWorks MDP (Model Definition Program) if you need the power of the more elaborate bigger sister ModelWorks.

2 - Features

Here are a few of the things Easy ModelWorks can do:

• interactively edit the specifications of your model system (interactive modeling)
• interactively control the numerical solving of your model (interactive simulation)
• save your work anytime to disk for later retrieval
• load (open) existing models from disk or from a "zoo" of predefined sample models
• interactively control initial conditions with a mouse click in a 2-dimensional state space graph (interactive phase portrait construction)
• simulate in power user mode existing research models of any complexity (made with RAMSES)
• the model "zoo" and the latter can easily be customized, e.g. by teachers, to particular subjects
• models are fully platform independent and can be freely ported back and forth between a Macintosh and an IBM PC.

However, some restrictions apply in Easy ModelWorks:

• Interactive modeling is only possible with one model at a time.
• An Easy ModelWorks model can only be of the type continuous time (DESS - Differential Equation System Specification) or discrete time (SQM - Sequential Machine), but not mixed. No support for DEVS - Discrete Event System Specification.
• The maximum system order is nine. If you don't like these restrictions, resort to the full fledged ModelWorks where none of these restrictions apply (Fischlin et al. 1994).

3 - Formal Interface

Easy ModelWorks offers a client (programer's) interface and supports the definition of a custom collection of sample models. To learn about the formal interface, notably all functions see:

• Overview of the Easy ModelWorks modules.
• Quick Reference containing all functions of Easy ModelWorks in a compact format.

4 - Availability

Easy ModelWorks is freeware (courtesy ETH Zurich).

Download it for:

• Mac Classic   (client interface supported)
• Windows   (client interface not supported)

For the latest information not contained in the on-line help of the downloaded software, consult the Easy ModelWorks Read Me:   pdf .

5 - Author

Easy ModelWorks has been developped by Andreas Fischlin.

6 - Cited References

Fischlin, A. (1991). Interactive Modeling and Simulation of Environmental Systems on Working Stations. In: Möller, D.P.F. & Richter, O. (eds.), Analysis of dynamic systems in medicine, biology, and ecology. Informatik-Fachberichte 275: 131-145.

Fischlin, A., Gyalistras, D., Roth, O., Ulrich, M., Thöny, J. & Nemecek, T., Bugmann, H. & Thommen, F. (1994). Model Works - an interactive simulation environment for personal computers and workstations. Systems Ecology Report No. 14, ETH Zurich, Switzerland, 324pp.

See also the Systems Ecology Publications and Reports.

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