Let X be a locally compact space, and T, a quasi-compact positive oper
ator on C-0(X), with positive spectral radius, r. Then the peripheral
spectrum of T is a finite set of poles containing r, and the residue o
f the resolvent of T at each peripheral pole is of finite rank. Using
the concept of closed absorbing set, we develop an iterative process t
hat gives the order, p, of r, some special bases of the algebraic eige
nspaces ker(T - r)(p) and ker(T - r)(p), and finally the dimension of
the algebraic eigenspace associated to each peripheral pole.