An algorithm for the poles at dimension four in the dimensional regularization procedure

One-loop Feynman diagrams, when regularized using the continuous dimension method, exhibit single poles at n=4, and these poles can be eliminated by a counterterm Delta L in the Lagrangian. In this paper a simple algorithm is derived to express Delta L in terms of the components of the Lagrangian L without performing integrations. It can be used in dimensional regularization, but also to derive Callan- Symanzik type equations for small distance behaviour in any renormalizable theory. The result of a calculation of the divergencies in quantum gravity is reported. (10 refs).