Solution of the epidemic model by homotopy perturbation method

In this article the problem of the spread of a non-fatal disease in a population which is assumed to have constant size over the period of the epidemic is considered. He’s homotopy perturbation method is employed to compute an approximation to the solution of the system of nonlinear ordinary differential equations governing on the problem. The results are compared with the results obtained by Adomian decomposition method. Some plots are presented to show the reliability and simplicity of the method.