Stability of a weighted L2 projection in a weighted Sobolev norm

We prove the stability of a weighted $L^2$ projection operator onto piecewise linear finite elements spaces in a weighted Sobolev norm. Namely, we consider the orthogonal projections $\pi _{N,\omega }$ from $L^2(\mathbb{D},1/\omega (x)\mathrm{d}x)$ to $\mathcal{X}_N$, where $\mathbb{D} \subset \math...

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Main Author: Averseng, Martin
Format: Article
Language:English
Published: Académie des sciences 2023-05-01
Series:Comptes Rendus. Mathématique
Online Access:https://comptes-rendus.academie-sciences.fr/mathematique/articles/10.5802/crmath.426/
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author Averseng, Martin
author_facet Averseng, Martin
author_sort Averseng, Martin
collection DOAJ
description We prove the stability of a weighted $L^2$ projection operator onto piecewise linear finite elements spaces in a weighted Sobolev norm. Namely, we consider the orthogonal projections $\pi _{N,\omega }$ from $L^2(\mathbb{D},1/\omega (x)\mathrm{d}x)$ to $\mathcal{X}_N$, where $\mathbb{D} \subset \mathbb{R}^2$ is the unit disk, $\omega (x) = \sqrt{1 - \vert x\vert ^2}$ and the spaces $(\mathcal{X}_N)_{N \in \mathbb{N}}$ consist of piecewise linear functions on a family of shape-regular and quasi-uniform triangulations of $\mathbb{D}$. We show that $\pi _{N,\omega }$ is stable in a weighted Sobolev norm, and prove an upper bound on the stability constant that does not depend on $N$. The result also holds when the disk $\mathbb{D}$ is replaced by a more general surface $\Gamma \subset \mathbb{R}^3$, replacing the weight $\omega $ by $\omega _\Gamma (x) := \sqrt{\mathrm{d}(x,\partial \Gamma )}$, the square root of the distance from $x$ to the manifold boundary of $\Gamma $.
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spelling doaj-art-799c51f7cdfe4557bcc61a861861f8f22025-02-07T11:07:37ZengAcadémie des sciencesComptes Rendus. Mathématique1778-35692023-05-01361G475776610.5802/crmath.42610.5802/crmath.426Stability of a weighted L2 projection in a weighted Sobolev normAverseng, Martin0Seminar for Applied Mathematics, ETH ZurichWe prove the stability of a weighted $L^2$ projection operator onto piecewise linear finite elements spaces in a weighted Sobolev norm. Namely, we consider the orthogonal projections $\pi _{N,\omega }$ from $L^2(\mathbb{D},1/\omega (x)\mathrm{d}x)$ to $\mathcal{X}_N$, where $\mathbb{D} \subset \mathbb{R}^2$ is the unit disk, $\omega (x) = \sqrt{1 - \vert x\vert ^2}$ and the spaces $(\mathcal{X}_N)_{N \in \mathbb{N}}$ consist of piecewise linear functions on a family of shape-regular and quasi-uniform triangulations of $\mathbb{D}$. We show that $\pi _{N,\omega }$ is stable in a weighted Sobolev norm, and prove an upper bound on the stability constant that does not depend on $N$. The result also holds when the disk $\mathbb{D}$ is replaced by a more general surface $\Gamma \subset \mathbb{R}^3$, replacing the weight $\omega $ by $\omega _\Gamma (x) := \sqrt{\mathrm{d}(x,\partial \Gamma )}$, the square root of the distance from $x$ to the manifold boundary of $\Gamma $.https://comptes-rendus.academie-sciences.fr/mathematique/articles/10.5802/crmath.426/
spellingShingle Averseng, Martin
Stability of a weighted L2 projection in a weighted Sobolev norm
Comptes Rendus. Mathématique
title Stability of a weighted L2 projection in a weighted Sobolev norm
title_full Stability of a weighted L2 projection in a weighted Sobolev norm
title_fullStr Stability of a weighted L2 projection in a weighted Sobolev norm
title_full_unstemmed Stability of a weighted L2 projection in a weighted Sobolev norm
title_short Stability of a weighted L2 projection in a weighted Sobolev norm
title_sort stability of a weighted l2 projection in a weighted sobolev norm
url https://comptes-rendus.academie-sciences.fr/mathematique/articles/10.5802/crmath.426/
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