Angular spectra of linear dynamical systems in discrete time

Fuente: arXiv
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Main Authors: Beyn, Wolf-Jürgen, Hüls, Thorsten
Format: Preprint
Published: 2024
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author Beyn, Wolf-Jürgen
Hüls, Thorsten
author_facet Beyn, Wolf-Jürgen
Hüls, Thorsten
contents In this work we introduce the notion of an angular spectrum for a linear discrete time nonautonomous dynamical system. The angular spectrum comprises all accumulation points of longtime averages formed by maximal principal angles between successive subspaces generated by the dynamical system. The angular spectrum is bounded by angular values which have previously been investigated by the authors. In this contribution we derive explicit formulas for the angular spectrum of some autonomous and specific nonautonomous systems. Based on a reduction principle we set up a numerical method for the general case; we investigate its convergence and apply the method to systems with a homoclinic orbit and a strange attractor. Our main theoretical result is a theorem on the invariance of the angular spectrum under summable perturbations of the given matrices (roughness theorem). It applies to systems with a so-called complete exponential dichotomy (CED), a concept which we introduce in this paper and which imposes more stringent conditions than those underlying the exponential dichotomy spectrum.
format Preprint
id arxiv_https___arxiv_org_abs_2404_02694
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Angular spectra of linear dynamical systems in discrete time
Beyn, Wolf-Jürgen
Hüls, Thorsten
Dynamical Systems
37E45, 37M25, 34D09, 65Q10
In this work we introduce the notion of an angular spectrum for a linear discrete time nonautonomous dynamical system. The angular spectrum comprises all accumulation points of longtime averages formed by maximal principal angles between successive subspaces generated by the dynamical system. The angular spectrum is bounded by angular values which have previously been investigated by the authors. In this contribution we derive explicit formulas for the angular spectrum of some autonomous and specific nonautonomous systems. Based on a reduction principle we set up a numerical method for the general case; we investigate its convergence and apply the method to systems with a homoclinic orbit and a strange attractor. Our main theoretical result is a theorem on the invariance of the angular spectrum under summable perturbations of the given matrices (roughness theorem). It applies to systems with a so-called complete exponential dichotomy (CED), a concept which we introduce in this paper and which imposes more stringent conditions than those underlying the exponential dichotomy spectrum.
title Angular spectra of linear dynamical systems in discrete time
topic Dynamical Systems
37E45, 37M25, 34D09, 65Q10
url https://arxiv.org/abs/2404.02694