  This paper deals with fractional differential equations, with dependence on a
Caputo fractional derivative of real order. The goal is to show, based on
concrete examples and experimental data from several experiments, that
fractional differential equations may model more efficiently certain problems
than ordinary differential equations. A numerical optimization approach based
on least squares approximation is used to determine the order of the fractional
operator that better describes real data, as well as other related parameters.
