Approximating the Perfect Sampling Grids for Computing the Eigenvalues of Toeplitz-like Matrices Using the Spectral Symbol

Fuente: arXiv
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Main Author: Ekström, Sven-Erik
Format: Preprint
Published: 2019
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author Ekström, Sven-Erik
author_facet Ekström, Sven-Erik
contents In a series of papers the author and others have studied an asymptotic expansion of the errors of the eigenvalue approximation, using the spectral symbol, in connection with Toeplitz (and Toeplitz-like) matrices, that is, $E_{j,n}$ in $λ_j(A_n)=f(θ_{j,n})+E_{j,n}$, $A_n=T_n(f)$, $f$ real-valued cosine polynomial. In this paper we instead study an asymptotic expansion of the errors of the equispaced sampling grids $θ_{j,n}$, compared to the exact grids $ξ_{j,n}$ (where $λ_j(A_n)=f(ξ_{j,n})$), that is, $E_{j,n}$ in $ξ_{j,n}=θ_{j,n}+E_{j,n}$. We present an algorithm to approximate the expansion. Finally we show numerically that this type of expansion works for various kind of Toeplitz-like matrices (Toeplitz, preconditioned Toeplitz, low-rank corrections of them). We critically discuss several specific examples and we demonstrate the superior numerical behavior of the present approach with respect to the previous ones.
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publishDate 2019
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spellingShingle Approximating the Perfect Sampling Grids for Computing the Eigenvalues of Toeplitz-like Matrices Using the Spectral Symbol
Ekström, Sven-Erik
Numerical Analysis
In a series of papers the author and others have studied an asymptotic expansion of the errors of the eigenvalue approximation, using the spectral symbol, in connection with Toeplitz (and Toeplitz-like) matrices, that is, $E_{j,n}$ in $λ_j(A_n)=f(θ_{j,n})+E_{j,n}$, $A_n=T_n(f)$, $f$ real-valued cosine polynomial. In this paper we instead study an asymptotic expansion of the errors of the equispaced sampling grids $θ_{j,n}$, compared to the exact grids $ξ_{j,n}$ (where $λ_j(A_n)=f(ξ_{j,n})$), that is, $E_{j,n}$ in $ξ_{j,n}=θ_{j,n}+E_{j,n}$. We present an algorithm to approximate the expansion. Finally we show numerically that this type of expansion works for various kind of Toeplitz-like matrices (Toeplitz, preconditioned Toeplitz, low-rank corrections of them). We critically discuss several specific examples and we demonstrate the superior numerical behavior of the present approach with respect to the previous ones.
title Approximating the Perfect Sampling Grids for Computing the Eigenvalues of Toeplitz-like Matrices Using the Spectral Symbol
topic Numerical Analysis
url https://arxiv.org/abs/1901.06917