Clicking on the picture makes it move. To change the recurrence and initial conditions you have to download the file and either edit it or run it under "wish". This was used to illustrate a talk I gave on the Vigre undergraduate lecture series on Algebra and wireless communication. Here are the transparencies (in PDF format) for the talk which has some explanations about the subject.
You can download the Tcl/Tk source text for the example by right-clicking here.
Other programs.
This page is maintained by Felipe Voloch