Error Estimates for Gauss--Christoffel Quadrature under Reduced Regularity Conditions

Fuente: arXiv
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Autori principali: Hamzehnejad, Mehdi, Salemi, Abbas
Natura: Preprint
Pubblicazione: 2025
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author Hamzehnejad, Mehdi
Salemi, Abbas
author_facet Hamzehnejad, Mehdi
Salemi, Abbas
contents Gauss--Christoffel quadrature is a fundamental method for numerical integration, and its convergence analysis is closely related to the decay of Chebyshev expansion coefficients. Classical estimates, including those due to Trefethen, are based on weighted bounded variation assumptions involving the singular weight $(1-x^{2})^{-1/2}$, which may be too restrictive for functions with limited regularity at the endpoints. In this paper, we establish a new error bound for Gauss--Christoffel quadrature under weakened regularity assumptions. The analysis relies on a new identity for higher-order derivatives of Chebyshev polynomials. As a consequence, we obtain an improved decay estimate for Chebyshev coefficients, where the classical weighted condition \[ V_{r}=\int_{-1}^{1}\frac{|f^{(r+1)}(x)|}{\sqrt{1-x^{2}}}\,dx \] is replaced by the weaker condition \[ U_{r}=\int_{-1}^{1}|f^{(r+1)}(x)|\,dx. \] This result leads to a corresponding error estimate for the Gauss--Christoffel quadrature rule, which is less restrictive than previous bounds. The approach is also extended to the Gauss--Gegenbauer case. Numerical experiments are provided to illustrate the theoretical results.
format Preprint
id arxiv_https___arxiv_org_abs_2512_23540
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Error Estimates for Gauss--Christoffel Quadrature under Reduced Regularity Conditions
Hamzehnejad, Mehdi
Salemi, Abbas
Numerical Analysis
65D32, 65D30, 41A55, 42C10
Gauss--Christoffel quadrature is a fundamental method for numerical integration, and its convergence analysis is closely related to the decay of Chebyshev expansion coefficients. Classical estimates, including those due to Trefethen, are based on weighted bounded variation assumptions involving the singular weight $(1-x^{2})^{-1/2}$, which may be too restrictive for functions with limited regularity at the endpoints. In this paper, we establish a new error bound for Gauss--Christoffel quadrature under weakened regularity assumptions. The analysis relies on a new identity for higher-order derivatives of Chebyshev polynomials. As a consequence, we obtain an improved decay estimate for Chebyshev coefficients, where the classical weighted condition \[ V_{r}=\int_{-1}^{1}\frac{|f^{(r+1)}(x)|}{\sqrt{1-x^{2}}}\,dx \] is replaced by the weaker condition \[ U_{r}=\int_{-1}^{1}|f^{(r+1)}(x)|\,dx. \] This result leads to a corresponding error estimate for the Gauss--Christoffel quadrature rule, which is less restrictive than previous bounds. The approach is also extended to the Gauss--Gegenbauer case. Numerical experiments are provided to illustrate the theoretical results.
title Error Estimates for Gauss--Christoffel Quadrature under Reduced Regularity Conditions
topic Numerical Analysis
65D32, 65D30, 41A55, 42C10
url https://arxiv.org/abs/2512.23540