Data-Driven Spectral Analysis with Pseudo-Resolvent Koopman Operator

This paper introduces a data-driven method to analyze the spectrum of the Koopman operator, a crucial tool in dynamical systems analysis. The method addresses the problem of spectral pollution, a common issue in finite-dimensional approximations of the Koopman operator, by constructing a pseudo-resolvent operator. The paper's significance lies in its ability to provide accurate spectral analysis from time-series data, suppressing spectral pollution and resolving closely spaced spectral components, which is validated through numerical experiments on various dynamical systems.