Electron. J. Diff. Eqns., Vol. 2004(2004), No. 139, pp. 1-17.

On Pontryagin-Rodygin's theorem for convergence of solutions of slow and fast systems

Tewfik Sari, Karim Yadi

Abstract:
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 fundamental tool is the Pontryagin and Rodygin theorem which describes the limiting behavior of the solutions in the continuously differentiable 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.

Submitted May 12, 2004. Published November 26, 2004.
Math Subject Classifications: 34D15, 34E15, 34E18.
Key Words: Singular perturbations; asymptotic stability; nonstandard analysis.

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Tewfik Sari
Laboratoire de Mathématiques et Applications
Université de Haute Alsace
4, rue des frères Lumière
68093, Mulhouse, France
email: Tewfik.Sari@uha.fr
Karim Yadi
Laboratoire de Mathématiques et Applications
Université de Haute Alsace
4, rue des frères Lumière
68093, Mulhouse, France
email: K.Yadi@uha.fr

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