“…In the last decades fractional calculus has been successfully used to model phenomena in different areas: diffusion problems, hydraulics, potential theory, control theory, electrochemistry, electromagnetism, viscoelasticity and nanotechnology (see for example [1,2,6,7,8,9,10,16,22,28,30,38] among others). Numerical schemes to calculate approximate solutions to fractional differential equations have also been introduced (see [5,24,35,39,40]).…”