On the convergence of numerical integration as a finite matrix approximation to multiplication operator

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Volume Title

A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Date

2023-06

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en

Pages

41

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Calcolo, Volume 60, issue 2

Abstract

We study the convergence of a family of numerical integration methods where the numerical integration is formulated as a finite matrix approximation to a multiplication operator. For bounded functions, convergence has already been established using the theory of strong operator convergence. In this article, we consider unbounded functions and domains which pose several difficulties compared to the bounded case. A natural choice of method for this study is the theory of strong resolvent convergence which has previously been mostly applied to study the convergence of approximations of differential operators. The existing theory already includes convergence theorems that can be used as proofs as such for a limited class of functions and extended for a wider class of functions in terms of function growth or discontinuity. The extended results apply to all self-adjoint operators, not just multiplication operators. We also show how Jensen’s operator inequality can be used to analyse the convergence of an improper numerical integral of a function bounded by an operator convex function.

Description

Funding Information: We thank the anonymous reviewers for their valuable comments. The work was supported by Academy of Finland (Grant no. 321891). Publisher Copyright: © 2023, The Author(s).

Keywords

Convergence, Multiplication operator, Numerical integration, Self-adjoint operator

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Citation

Sarmavuori, J & Särkkä, S 2023, 'On the convergence of numerical integration as a finite matrix approximation to multiplication operator', Calcolo, vol. 60, no. 2, 22. https://doi.org/10.1007/s10092-023-00518-4