ON PONTRYAGIN-RODYGIN'S THEOREM FOR CONVERGENCE OF SOLUTIONS OF SLOW AND FAST SYSTEMS

In this paper we study fast and slow systems for which the fast dynamics has limit cycles, for all fixed values of the slow variables. The fun- damental tool is the Pontryagin and Rodygin theorem which describes the limiting behavior of the solutions in the continuously dierentiable case, when the cycles are exponentially stable. We extend this result to the continuous case, and exponential stability is replaced by asymptotic stability. We give two examples with numerical simulations to illustrate the problem. Our results are formulated in classical mathematics. They are proved using Nonstandard Analysis.