The problem of summing a set of mutual recurrence relations with constant coefficients is investigated. A method is presented for summing an order d system of the form A(n) = ∑d i=1 MiA(n − i) + G(n), where A,G : N → K and M1, . . . ,Md ∈ Mm(K) for some field K and natural number m. The procedure expresses the sum ∑n i=0 A(i) in terms of A(n), . . . , A(n− d), initial conditions and sums of the...