“…After these pioneer works, many other extensive researches have been done on the development of numerical methods for FOCPs. For instance, we can refer to Oustaloup recursive approximation [22], direct methods based on pseudo-state-space formulations of FOCP [36], spectral methods based on orthogonal polynomials and fractional operational matrices [37,38,39,40,41,42,43], Legendre multiwavelet collocation methods [44], direct methods based on Bernstein polynomials [45,46,47], nonstandard finite difference methods [48], linear programming approaches [49], integral fractional pseudospectral methods [50], direct methods based on Ritz's techniques [51,52], the epsilon-Ritz method [53], direct methods based on hybrid block-pulse with other basis functions [54,55], pseudospectral methods based on Legendre Müntz basis functions [56], dynamic Hamilton-Jacobi-Bellman methods [57], penalty and variational methods [58], control parameterization methods [59], differential and integral fractional pseudospectral methods [60], as well as other numerical techniques [61,62,63]. Efforts were also done to derive optimality conditions for special types of FOCPs, such as bang-bang FOCPs [64] and free final and terminal time problems [65,66].…”