Welcome to Systo...

... an open, adaptable and lightweight approach for viewing, building and running systems models in web pages.

These pages have been tested and appear to work in Chrome, Firefox and Safari. They probably will not work in Internet Explorer.

Systo is based on a collection of widgets, each of which does a specific job: for example, display a model diagram, or display the results of simulating the behaviour of a model. These widgets can be made by anyone, and can live anywhere on the internet. Web page developers can then choose any combination of these, and incorporate them into their own web page.

The basic idea is that:

Systo models can be built and live anywhere on the internet;
Systo widgets can be built and live anywhere on the internet;
Any web page developer can, using little more than conventional HTML, build a web page which uses one or more Systo widgets to give users access to one or more Systo models.

Some of these web pages might be restricted to a single model using a small number of widgets. Others may be very broad, giving users access to many models (perhaps stored on a web database), along with a range of widgets for working with these models.

A "Hello, world" example

This is the classic predator-prey model, conventionally expressed in terms of "rabbits and foxes".

You can interact with the model diagram in various ways:

You can zoom in, zoom out and zoom-to-fit using the buttons on the left of the diagram.
You can resize the box the diagram is in, by dragging on the right or bottom edges.
You can drag the diagram around, useful if you have a large diagram.
You can show more detail (parameters and influence arrows): just click on the 'Show all' button.
You can even re-arrange the nodes in the diagram (stocks, clouds and variables), by dragging them around!

You can also explore the dynamic behaviour of the model. Move the sliders for the initial population size of the rabbits and foxes, or the various parameters, and observe:

how the graphs showing the rabbit and the fox population size; and
how some statistics derived from the model results (the maximum for the two populations, and the cycle period)

automatically update as you move the sliders. The computer is continuously re-running the model as you do this.

The maximum value for the number of foxes is and for the number of rabbits is . The cycle period is years.