Article

# Multiscale matrix pencils for separable reconstruction problems

## Details

Citation

Cuyt A & Lee W (2023) Multiscale matrix pencils for separable reconstruction problems. Numerical Algorithms. https://doi.org/10.1007/s11075-023-01564-3

Abstract
The nonlinear inverse problem of exponential data fitting is separable since the fitting function is a linear combination of parameterized exponential functions, thus allowing to solve for the linear coefficients separately from the nonlinear parameters. The matrix pencil method, which reformulates the problem statement into a generalized eigenvalue problem for the nonlinear parameters and a structured linear system for the linear parameters, is generally considered as the more stable method to solve the problem computationally. In Section 2 the matrix pencil associated with the classical complex exponential fitting or sparse interpolation problem is summarized and the concepts of dilation and translation are introduced to obtain matrix pencils at different scales. Exponential analysis was earlier generalized to the use of several polynomial basis functions and some operator eigenfunctions. However, in most generalizations a computational scheme in terms of an eigenvalue problem is lacking. In the subsequent Sections 3–6 the matrix pencil formulation, including the dilation and translation paradigm, is generalized to more functions. Each of these periodic, polynomial or special function classes needs a tailored approach, where optimal use is made of the properties of the parameterized elementary or special function used in the sparse interpolation problem under consideration. With each generalization a structured linear matrix pencil is associated, immediately leading to a computational scheme for the nonlinear and linear parameters, respectively from a generalized eigenvalue problem and one or more structured linear systems. Finally, in Section 7 we illustrate the new methods.

Keywords
Prony problems; Separable problems; Parametric methods; Sparse interpolation; Dilation; Translation; Structured matrix; Generalized eigenvalue problem

Journal
Numerical Algorithms

Status In Press European Commission (Horizon 2020) and The Carnegie Trust 30/06/2023 14/04/2023 http://hdl.handle.net/1893/35573 1017-1398 1572-9265

## People

Dr Wen-shin Lee

Lecturer, Computing Science and Mathematics - Division