How to implement SIRS model? I have been given a project to implement an SIRS model. While searching how to do it, I found this site and a question related to epidemic model. It is very much related to my project and is quite helpful. However, since I'm new to this topic, can you please help me on how to start implementing SIRS model. I have to implement one simulator in Java. I don't have any idea on how to start the implementation. I will be really grateful if you help me. 
 A: There is an open source epidemiology modeling package called STEM. It is Java-based and built on top of Eclipse. You can build your model on top of this. 
On the other hand, SIRS is a relatively straight-forward differential equations model. You can simulate it by take short time intervals and computing the quantities directly. 
A: There are many ways to implement and SIR-type compartmental model in the language of your choice. Likely the most straightforward is to find an ordinary differential equation solver of your choice in Java (there are likely many), and go from there.
Unfortunately their Java implementations aren't up yet, but Keeling and Rohani have code to accompany their book in C++, Fortran, MATLAB and Python (some combination of them for each) here: http://www.ModelingInfectiousDiseases.org/
This is a StackOverflow question discussing exactly your problem: https://stackoverflow.com/questions/4357061/differential-equations-in-java with an implementation of the model using Euler's method.
