Abstract

Conley indices and Morse decompositions of flows can be found by using algorithms which rigorously analyze discrete dynamical systems. This usually involves integrating a time discretization of the flow using interval arithmetic. We compare the old idea of fixing a time step as a parameter to a time step continuously varying in phase space. We present an example where this second strategy necessarily yields better numerical outputs and prove that our outputs yield a valid Morse decomposition of the given flow.

Highlights

  • While the numerical approximation of ordinary differential equations has a long history, the systematic study of how to compute time invariant structures began in the 1980s

  • Rigorous computations of these structures is an even more recent phenomenon. These latter efforts can be roughly divided into two approaches: direct computation of invariant sets, e.g., periodic orbits, heteroclinic and homoclinic orbits, invariant manifolds, and a more indirect approach based on identification of isolating neighborhoods

  • From a theoretical perspective this approach allows us to recover the local and global dynamics associated with isolated invariant sets generated by ordinary differential equations

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Summary

INTRODUCTION

While the numerical approximation of ordinary differential equations has a long history, the systematic study of how to compute time invariant structures began in the 1980s. From a theoretical perspective this approach allows us to recover the local and global dynamics associated with isolated invariant sets generated by ordinary differential equations. As indicated above, [14, Theorem 1] guarantees that on the level of isolated invariant sets the dynamics of φh captures the dynamics of φ Since this is not always true for a φτ with varying time steps we prove Lemma 3.18, which provides a criterion under which we obtain the desired isolation. Their proofs require some background in dynamical systems, which can be found in [22] and other textbooks about the field

A NUMERICAL EXAMPLE
THEORETICAL JUSTIFICATION
FINAL REMARKS
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