“…As it is known, the spectral method is one of the flexible methods of discretization for most types of differential equations [38][39][40]. Historically, spectral method has been relegated to fractional calculus, but in few years, it has been successfully applied for the fractional equation models based on the different types of orthogonal polynomials such as Block pulse functions [41,42], Legendre polynomials [43][44][45][46], Chebyshev polynomials [47][48][49], Laguerre polynomials [50][51][52][53], and Bernstein polynomials [54][55][56]. Doha et al [57] introduced the shifted Jacobi operational matrix of fractional derivative which is based on Jacobi tau method for solving numerically linear multiterm fractional differential equations with initial or boundary conditions.…”