Local spectral approximation of unbounded operators: non-asymptotic and unified error quantification for subspace methods

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1. Verfasser: Stroschein, Timothy
Format: Preprint
Veröffentlicht: 2025
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_version_ 1866909980116910080
author Stroschein, Timothy
author_facet Stroschein, Timothy
contents We introduce a framework for subspace methods which approximate the spectra of self-adjoint, unbounded operators in a local region. Using the projection-valued measure, we derive integrated spectral inequalities that also apply to unbounded operators. Our framework is non-asymptotic, gap-independent, and enables a unified error quantification of numerical routines subject to multiple error sources. Furthermore, we formalize the class of methods applicable to our framework, and establish a rigorous foundation for dimension detection in the presence of noise as solution to frequent numerical artifacts such as spectral pollution. The practical relevance of this non-asymptotic analysis is substantiated by its recent application to sampled prolate filter diagonalization, where it successfully predicted a sharp accuracy transition linking spectral density to the minimal observation time required to decompose a signal.
format Preprint
id arxiv_https___arxiv_org_abs_2505_07513
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Local spectral approximation of unbounded operators: non-asymptotic and unified error quantification for subspace methods
Stroschein, Timothy
Numerical Analysis
Mathematical Physics
Spectral Theory
65F15, 65J10, 47A75, 47B25, 47A58
G.1.2; G.1.3
We introduce a framework for subspace methods which approximate the spectra of self-adjoint, unbounded operators in a local region. Using the projection-valued measure, we derive integrated spectral inequalities that also apply to unbounded operators. Our framework is non-asymptotic, gap-independent, and enables a unified error quantification of numerical routines subject to multiple error sources. Furthermore, we formalize the class of methods applicable to our framework, and establish a rigorous foundation for dimension detection in the presence of noise as solution to frequent numerical artifacts such as spectral pollution. The practical relevance of this non-asymptotic analysis is substantiated by its recent application to sampled prolate filter diagonalization, where it successfully predicted a sharp accuracy transition linking spectral density to the minimal observation time required to decompose a signal.
title Local spectral approximation of unbounded operators: non-asymptotic and unified error quantification for subspace methods
topic Numerical Analysis
Mathematical Physics
Spectral Theory
65F15, 65J10, 47A75, 47B25, 47A58
G.1.2; G.1.3
url https://arxiv.org/abs/2505.07513