“…The development of numerical procedures for approximating the action of f (A) to a vector has received considerable attention in the last two decades. This is possibly related to the significant increase of methods for the numerical solution of partial differential equations that either directly approximate the exact solution (see, e.g., [20], [47], [24], [23]), or employ matrix functional integrators; see, e.g., [30], [28], [29]. In addition, large-scale advanced scientific applications often require function evaluations of matrices; see, e.g., [5], [43], [55], [17].…”