“…Denote α = τ 2h 2 ; note that, for the particular application concerning the study of image processing, the spatial discretization step size h is here mentioned for memory; in fact in image processing, h is defined implicitly by the distance between two pixels and can be fixed to the value one (see [19] and [24]); in the sequel, we will see that the value of h has no effect with respect to the behavior of the studied algorithms. Denote also by U (k) the vector of components u (k) i, j that approximates u(x i , y j , t k ); in the sequel U (0) is given by the components of u 0 (x i , y j ) of the initial condition arising in (9). Then, classically, the explicit scheme is given by…”