Bessa, Mário2023-06-022023-06-022012M. Bessa, Perturbations of Mathieu Equations with Parametric Excitation of Large Period, Advances in Dynamical Systems and Applications, 7, 1, 17–30 (2012)0973-5321http://hdl.handle.net/10400.2/13967We consider a linear differential system of Mathieu equations with periodic coefficients over periodic closed orbits and we prove that, arbitrarily close to this system, there is a linear differential system of Hamiltonian damped Mathieu equa- tions with periodic coefficients over periodic closed orbits such that, all but a finite number of closed periodic coefficients, have unstable solutions. The perturbations will be performed in the periodic coefficients.engMathieu equationCharacteristic multipliersLinear differential systemsjournal article