- Journal Home
- Volume 18 - 2025
- Volume 17 - 2024
- Volume 16 - 2023
- Volume 15 - 2022
- Volume 14 - 2021
- Volume 13 - 2020
- Volume 12 - 2019
- Volume 11 - 2018
- Volume 10 - 2017
- Volume 9 - 2016
- Volume 8 - 2015
- Volume 7 - 2014
- Volume 6 - 2013
- Volume 5 - 2012
- Volume 4 - 2011
- Volume 3 - 2010
- Volume 2 - 2009
- Volume 1 - 2008
Numer. Math. Theor. Meth. Appl., 8 (2015), pp. 136-148.
Published online: 2015-08
Cited by
- BibTex
- RIS
- TXT
A shifted Laplacian operator is obtained from the Helmholtz operator by adding a complex damping. It serves as a basic tool in the most successful multigrid approach for solving highly indefinite Helmholtz equations — a Shifted Laplacian preconditioner for Krylov-type methods. Such preconditioning significantly accelerates Krylov iterations, much more so than the multigrid based on original Helmholtz equations. In this paper, we compare approximation and relaxation properties of the Helmholtz operator with and without the complex shift, and, based on our observations, propose a new hybrid approach that combines the two. Our analytical conclusions are supported by two-dimensional numerical results.
}, issn = {2079-7338}, doi = {https://doi.org/10.4208/nmtma.2015.w03si}, url = {http://global-sci.org/intro/article_detail/nmtma/12403.html} }A shifted Laplacian operator is obtained from the Helmholtz operator by adding a complex damping. It serves as a basic tool in the most successful multigrid approach for solving highly indefinite Helmholtz equations — a Shifted Laplacian preconditioner for Krylov-type methods. Such preconditioning significantly accelerates Krylov iterations, much more so than the multigrid based on original Helmholtz equations. In this paper, we compare approximation and relaxation properties of the Helmholtz operator with and without the complex shift, and, based on our observations, propose a new hybrid approach that combines the two. Our analytical conclusions are supported by two-dimensional numerical results.