Moghaddam, Behrouz ParsaMachado, J. A. Tenreiro2017-01-262016http://hdl.handle.net/10400.22/9441This paper proposes accurate and robust algorithms for approximating variable order fractional derivatives of arbitrary order. The proposed schemes are based on finite difference approximations.We compare the performance of algorithms by introducing a new formulation of experimental convergence order. Two initial value problems are considered and solved by means of the proposed methods. Numerical results are provided justifying the usefulness of the proposed methods.engVariable order fractional calculusFinite difference approximationConvergence orderNumerical methodjournal article10.1007/s10915-016-0343-1