Simulation Modelling Tool EJS — Paul Kates

Simulation Modelling Tool EJS

EJS (Easy Java Simulations) is an active, open-source software project designed for instructors and students to graphically model differential equations.

It allows selecting graphical display elements like graphs, input elements like sliders and parameter variable boxes and output animation elements
to build a simulation of a differential equation model with little to no programming. Equation solvers are built in, as are the basic user interface elements that can be so time-consuming to add into programs.  Should you wish to go beyond the basic features of the software, optional programming in Java can be added.

Here is an example of planetary motion with a graphical interface using control buttons, input boxes and an animated orbit.  Other examples in physics, chemistry, mathematics and biology are listed on the EJS Demos/Examples page.

Computer simulation offers the advantages of visually seeing the behaviour of the model plus being able to interact with it and study it.  And, being programmed in Java, the simulations can be created and used on every computer platform (Windows, Mac, Linux).

The following two links give a longer more detailed description of EJS.  They are well worth reading.

When you begin playing with your own EJS programs, look for guidance and inspiration in the source code (the models, and gui elements) of the many EJS models available at the Open Source Physics project and in the tips offered in the EJS discussion forum.

Published by

Paul Kates

Centre for Teaching Excellence (CTE) Liaison to the Faculty of Mathematics (

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