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Main Authors: Monfared, Zahra, Malhotra, Saksham, Hajime, Sekiya, Kevrekidis, Ioannis, Dietrich, Felix
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2604.21825
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author Monfared, Zahra
Malhotra, Saksham
Hajime, Sekiya
Kevrekidis, Ioannis
Dietrich, Felix
author_facet Monfared, Zahra
Malhotra, Saksham
Hajime, Sekiya
Kevrekidis, Ioannis
Dietrich, Felix
contents For continuous-time dynamical systems with reversible trajectories, the nowhere-vanishing eigenfunctions of the Koopman operator of the system form a multiplicative group. Here, we exploit this property to accelerate the systematic numerical computation of the eigenspaces of the operator. Given a small set of (so-called ``principal'') eigenfunctions that are approximated conventionally, we can obtain a much larger set by constructing polynomials of the principal eigenfunctions. This enriches the set, and thus allows us to more accurately represent application-specific observables. Often, eigenfunctions exhibit localized singularities (e.g. in simple, one-dimensional problems with multiple steady states) or extended ones (e.g. in simple, two-dimensional problems possessing a limit cycle, or a separatrix); we discuss eigenfunction matching/continuation across such singularities. By handling eigenfunction singularities and enabling their continuation, our approach supports learning consistent global representations from locally sampled data. This is particularly relevant for multistable systems and applications with sparse or fragmented measurements.
format Preprint
id arxiv_https___arxiv_org_abs_2604_21825
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle On the algebra of Koopman eigenfunctions and on some of their infinities
Monfared, Zahra
Malhotra, Saksham
Hajime, Sekiya
Kevrekidis, Ioannis
Dietrich, Felix
Dynamical Systems
Machine Learning
Numerical Analysis
For continuous-time dynamical systems with reversible trajectories, the nowhere-vanishing eigenfunctions of the Koopman operator of the system form a multiplicative group. Here, we exploit this property to accelerate the systematic numerical computation of the eigenspaces of the operator. Given a small set of (so-called ``principal'') eigenfunctions that are approximated conventionally, we can obtain a much larger set by constructing polynomials of the principal eigenfunctions. This enriches the set, and thus allows us to more accurately represent application-specific observables. Often, eigenfunctions exhibit localized singularities (e.g. in simple, one-dimensional problems with multiple steady states) or extended ones (e.g. in simple, two-dimensional problems possessing a limit cycle, or a separatrix); we discuss eigenfunction matching/continuation across such singularities. By handling eigenfunction singularities and enabling their continuation, our approach supports learning consistent global representations from locally sampled data. This is particularly relevant for multistable systems and applications with sparse or fragmented measurements.
title On the algebra of Koopman eigenfunctions and on some of their infinities
topic Dynamical Systems
Machine Learning
Numerical Analysis
url https://arxiv.org/abs/2604.21825