2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/163337A solution of the nonlinear Klein-Gordon equation perturbed by a parametric driver is studied. The frequency of the parametric perturbation varies slowly and passes through a resonant value. It yields a change in a solution. We obtain a connection formula for the asymptotic solution before and after the resonance.20 pages, 2 figurasMathematical Physics35Q51, 35Q55text