In this paper, the problem of single-well, double-well and double-hump Van der Pol–Duffing
oscillator is studied. Governing equation is solved analytically and numerically using `Homotopy
perturbation Method` (HPM) and `Variational Iteration Method` (VIM). Present solutions gives an
expression which can be used in wide range of time for all domain of response. Comparisons of the
obtained solutions with numerical results show that these methods are effective and convenient for
solving this problem.
