Resumen
A first order method is considered for the discretization in time of an integro-differential equation, which can be written as $D^{\alpha} u(t) = A u(t) + f(t)$, $1 < \alpha < 2$, where $A : D(A) \subset X \to X$ is a sectorial operator in a Banach space X. Qualitative properties of the numerical solution, such as contractivity and positivity, are studied. A numerical illustration is provided.