Abstract
In this paper, a Van der Pol-Duffing oscillator is studied. Governing equations are solved by using a newly proposed method, namely; the "Homotopy Perturbation Transform Method" (HPTM). The beauty of the paper is error analysis between the exact solutions, approximate solutions and numerical solutions, which shows that our approximate solutions converge very rapidly to the exact solutions. HPTM is not limited to the small parameter, such as in the classical perturbation method. The method gives an analytical solution in the form of a convergent series with easily computable components, requiring no linearization or small perturbation. Results indicate that this technique is very effective and simple for solving nonlinear oscillatory systems. The solution procedure confirms that this method can be easily extended to other kinds of nonlinear oscillator equations. (C) 2012 Sharif University of Technology. Production and hosting by Elsevier B. V. All rights reserved.