1. Stability Analysis of a Simple Discretization Method for a Class of Strongly Singular Integral Equations
- Author
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Costabel, Martin, Dauge, Monique, Nedaiasl, Khadijeh, Institut de Recherche Mathématique de Rennes (IRMAR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École normale supérieure - Rennes (ENS Rennes)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-INSTITUT AGRO Agrocampus Ouest, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), and Institute for Advanced Studies in Basic Sciences [Zanjan] (IASBS)
- Subjects
volume integral equation ,discrete dipole approximation ,numerical stability ,FOS: Mathematics ,volume integral equation, strongly singular kernel, delta-delta discretization, discrete dipole approximation, numerical stability ,65R20 ,Mathematics - Numerical Analysis ,Numerical Analysis (math.NA) ,[MATH]Mathematics [math] ,strongly singular kernel ,delta-delta discretization ,MSC: 65R20, 45E10, 47A12, 65B10, 78M99 - Abstract
Motivated by the discrete dipole approximation (DDA) for the scattering of electromagnetic waves by a dielectric obstacle that can be considered as a simple discretization of a Lippmann-Schwinger style volume integral equation for time-harmonic Maxwell equations, we analyze an analogous discretization of convolution operators with strongly singular kernels. For a class of kernel functions that includes the finite Hilbert transformation in 1D and the principal part of the Maxwell volume integral operator used for DDA in dimensions 2 and 3, we show that the method, which does not fit into known frameworks of projection methods, can nevertheless be considered as a finite section method for an infinite block Toeplitz matrix. The symbol of this matrix is given by a Fourier series that does not converge absolutely. We use Ewald's method to obtain an exponentially fast convergent series representation of this symbol and show that it is a bounded function, thereby allowing to describe the spectrum and the numerical range of the matrix. It turns out that this numerical range includes the numerical range of the integral operator, but that it is in some cases strictly larger. In these cases the discretization method does not provide a spectrally correct approximation, and while it is stable for a large range of the spectral parameter $\lambda$, there are values of $\lambda$ for which the singular integral equation is well posed, but the discretization method is unstable., Comment: 34 pages, 7 figures, In V2: added 2 new references in the introduction
- Published
- 2023