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arXiv · 1512.07286

Measuring quasiperiodicity

Suddhasattwa Das·Chris B. Dock·Yoshitaka Saiki·Martin Salgado-Flores·Evelyn Sander·Jin Wu·James A. Yorke
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Abstract

The Birkhoff Ergodic Theorem asserts under mild conditions that Birkhoff averages (i.e. time averages computed along a trajectory) converge to the space average. For sufficiently smooth systems, our small modification of numerical Birkhoff averages significantly speeds the convergence rate for quasiperiodic trajectories -- by a factor of $10^{25}$ for 30-digit precision arithmetic, making it a useful computational tool for autonomous dynamical systems. Many dynamical systems and especially Hamiltonian systems are a complex mix of chaotic and quasiperiodic behaviors, and chaotic trajectories near quasiperiodic points can have long near-quasiperiodic transients. Our method can help determine which initial points are in a quasiperiodic set and which are chaotic. We use our {\bf weighted Birkhoff average} to study quasiperiodic systems, to distinguishing between chaos and quasiperiodicity, and for computing rotation numbers for self-intersecting curves in the plane. Furthermore we introduce the Embedding Continuation Method which is a significantly simpler, general method for computing rotation numbers.

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Suddhasattwa Das, Chris B. Dock, Yoshitaka Saiki, Martin Salgado-Flores, Evelyn Sander, Jin Wu, James A. Yorke. 2015-12-22. Measuring quasiperiodicity. https://doi.org/10.1209/0295-5075%2F114%2F40005

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