We use the Cayley-Hamilton theorem and the sequence of Horner polynomials associated with a polynomial w(z) to obtain explicit formulas for functions of the form f (tA), where f is defined by a convergent power series and A is a square matrix. We use a well-known explicit formula for the resolvent of A and show that f (tA) is the Hadamard product of f (t) and the function (I − tA) −1 , which is easily obtained from the resolvent.