“…Since most fractional differential equations do not have exact analytic solutions, approximate and numerical techniques, are used extensively, such as homotopy analysis method [10,16,31], homotopy perturbation method [20,21], variational iteration method [15,17,18,19], Chebyshev spectral method [12,13], c 2014 Diogenes Co., Sofia pp. 382-400 , DOI: 10.2478/s13540-014-0176-2 new iterative method [9,22,23,24], orthogonal polynomial method [33,36], Oldham-Spanier L1 method [32], Grunwald-Letnikov method [33,14], fractional Adams method [11], and several other methods [33,27,28,46].…”