A Riemann--Hilbert approach to computing the inverse spectral map for measures supported on disjoint intervals

Fuente: arXiv
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Auteurs principaux: Ballew, Cade, Trogdon, Thomas
Format: Preprint
Publié: 2023
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author Ballew, Cade
Trogdon, Thomas
author_facet Ballew, Cade
Trogdon, Thomas
contents We develop a numerical method for computing with orthogonal polynomials that are orthogonal on multiple, disjoint intervals for which analytical formulae are currently unknown. Our approach exploits the Fokas--Its--Kitaev Riemann--Hilbert representation of the orthogonal polynomials to produce an $\mathrm{O}(N)$ method to compute the first $N$ recurrence coefficients. The method can also be used for pointwise evaluation of the polynomials and their Cauchy transforms throughout the complex plane. The method encodes the singularity behavior of weight functions using weighted Cauchy integrals of Chebyshev polynomials. This greatly improves the efficiency of the method, outperforming other available techniques. We demonstrate the fast convergence of our method and present applications to integrable systems and approximation theory.
format Preprint
id arxiv_https___arxiv_org_abs_2302_12930
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle A Riemann--Hilbert approach to computing the inverse spectral map for measures supported on disjoint intervals
Ballew, Cade
Trogdon, Thomas
Numerical Analysis
Complex Variables
42C05, 65E05, 33C47
We develop a numerical method for computing with orthogonal polynomials that are orthogonal on multiple, disjoint intervals for which analytical formulae are currently unknown. Our approach exploits the Fokas--Its--Kitaev Riemann--Hilbert representation of the orthogonal polynomials to produce an $\mathrm{O}(N)$ method to compute the first $N$ recurrence coefficients. The method can also be used for pointwise evaluation of the polynomials and their Cauchy transforms throughout the complex plane. The method encodes the singularity behavior of weight functions using weighted Cauchy integrals of Chebyshev polynomials. This greatly improves the efficiency of the method, outperforming other available techniques. We demonstrate the fast convergence of our method and present applications to integrable systems and approximation theory.
title A Riemann--Hilbert approach to computing the inverse spectral map for measures supported on disjoint intervals
topic Numerical Analysis
Complex Variables
42C05, 65E05, 33C47
url https://arxiv.org/abs/2302.12930