Figure 1: Plots of the residuals, blue: ADM, green: NIM, red: HPM, black: OHAM and dashed: DTM. In this figure, a comparison of the residuals is shown graphically, and it reveals that OHAM is more suitable technique for this problem. One can easily observe that the curve of the OHAM residual is approximately normally distributed while the curves of the residuals of other methods are -shaped and highly skewed.