We describe a code that evaluates the stability, the position and the width of resonances in four-dimensional symplectic mappings. The code is based on the computation of the resonant perturbative series through the program ARES, and on the analysis of the resonant orbits of the interpolating Hamiltonian. The code is dedicated to the study and to the comparison of the nonlinear behaviour in one-turn betatronic maps. (Source: