On the variational equations associated with a Lagrangian

In a previous publication, Broucke [1] has studied the symplectic properties of the variational equations of a Lagrangian of a very particular form, withconstant coefficients. In this article, we generalize his results to the case of an arbitrary Lagrangian. We show that the characteristic exponents of a periodic solution can be computed in Lagrangian formulation as well as in the more usual Hamiltonian formulation.