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In this paper, we introduce the fractional Fourier series on the fractional torus and study some basic facts of fractional Fourier series, such as fractional convolution and fractional approximation. Meanwhile, fractional Fourier inversion…

Functional Analysis · Mathematics 2024-07-08 Zunwei Fu , Xianming Hou , Qingyan Wu

In this paper, a new semi-discrete version of the Carleman estimate-based convexification globally convergent numerical method is developed. It is used for the delivery of the starting point for the training procedure of deep learning. An…

Analysis of PDEs · Mathematics 2026-02-23 Michael V. Klibanov , Kirill V. Golubnichiy , Benjamin Jiang

An approximately globally convergent numerical method for a 3d Coefficient Inverse Problem for a hyperbolic equation with backscattering data is presented. A new approximate mathematical model is presented. An approximation is used only on…

Mathematical Physics · Physics 2012-09-18 Larisa Beilina , Michael V. Klibanov

Generalized Fourier series with orthogonal polynomial bases have useful applications in several fields, including differential equations, pattern recognition, and image and signal processing. However, computing the generalized Fourier…

Numerical Analysis · Mathematics 2015-02-09 Ashley Prater

The purpose of this paper is to introduce several new convolution operators, generated by some known probability densities. By using the inverse Fourier transform and taking inverse steps (in the analogues of the classical procedures used…

Classical Analysis and ODEs · Mathematics 2017-09-15 Sorin G. Gal

In 1965 A.N. Tikhonov, the founder of the theory of Ill-Posed and Inverse Problems, has posed an coefficient inverse problem of the recovery of the unknown electric conductivity coefficient from measurements of the back reflected electrical…

Numerical Analysis · Mathematics 2025-02-21 Michael V. Klibanov

For the first time, a globally convergent numerical method is presented for ill-posed Cauchy problems for quasilinear PDEs. The key idea is to use Carleman Weight Functions to construct globally strictly convex Tikhonov-like cost…

Analysis of PDEs · Mathematics 2015-02-20 Michael V. Klibanov

An $\left( n+1\right) -$D coefficient inverse problem for the radiative stationary transport equation is considered for the first time. A globally convergent so-called convexification numerical \ method is developed and its convergence…

Numerical Analysis · Mathematics 2022-06-24 Michael V. Klibanov , Jingzhi Li , Loc H. Nguyen , Zhipeng Yang

This paper uses the machinery of almost periodic functions to prove that even without uniform convergence the connection between a pair of almost periodic functions and the constants of the associated Fourier series exists for both the…

Number Theory · Mathematics 2015-07-29 John Washburn

In this work, we construct the Born and inverse Born approximation and series to recover two function-valued coefficients in the Helmholtz equation for inverse scattering problems from the scattering data at two different frequencies. An…

Numerical Analysis · Mathematics 2025-03-18 Fioralba Cakoni , Shixu Meng , Zehui Zhou

We develop an efficient and convergent numerical method for solving the inverse problem of determining the potential of nonlinear hyperbolic equations from lateral Cauchy data. In our numerical method we construct a sequence of linear…

Numerical Analysis · Mathematics 2022-04-14 Dinh-Liem Nguyen , Loc Nguyen , Trung Truong

We study the finite convergence of iterative methods for solving convex feasibility problems. Our key assumptions are that the interior of the solution set is nonempty and that certain overrelaxation parameters converge to zero, but with a…

Optimization and Control · Mathematics 2021-07-13 Victor I. Kolobov , Simeon Reich , Rafał Zalas

In this paper, we introduce an algorithm that provides approximate solutions to semi-linear ordinary differential equations with highly oscillatory solutions, which, after an appropriate change of variables, can be rewritten as…

Numerical Analysis · Mathematics 2025-02-13 M. P. Calvo , J. Makazaga , A. Murua

Using nonstandard methods, we show that the time dependent Fourier series of any smooth function F, solving the wave equation, on a finite closed interval, with vanishing boundary conditions, converges uniformly to F.

Analysis of PDEs · Mathematics 2014-10-07 Tristram de Piro

This paper addresses Tikhonov like regularization methods with convex penalty functionals for solving nonlinear ill-posed operator equations formulated in Banach or, more general, topological spaces. We present an approach for proving…

Numerical Analysis · Mathematics 2009-06-19 Jens Geissler , Bernd Hofmann

We present and analyze a novel wavelet-Fourier technique for the numerical treatment of multidimensional advection-diffusion-reaction equations based on the CORSING (COmpRessed SolvING) paradigm. Combining the Petrov-Galerkin technique with…

Numerical Analysis · Mathematics 2020-05-18 Simone Brugiapaglia , Stefano Micheletti , Fabio Nobile , Simona Perotto

We consider Tikhonov-type variational regularization of ill-posed linear operator equations in Banach spaces with general convex penalty functionals. Upper bounds for certain error measures expressing the distance between exact and…

Numerical Analysis · Mathematics 2017-12-06 Jens Flemming

In this paper we consider convex Tikhonov regularisation for the solution of linear operator equations on Hilbert spaces. We show that standard fractional source conditions can be employed in order to derive convergence rates in terms of…

Optimization and Control · Mathematics 2020-02-24 Markus Grasmair

A computationally efficient method to solve non-convex programming problems with linear equality constraints is presented. The proposed method is based on a recursively feasible and descending sequential convex programming procedure proven…

Optimization and Control · Mathematics 2018-10-25 Josep Virgili-Llop , Marcello Romano

We investigate algorithms for reconstructing a convex body $K$ in $\mathbb {R}^n$ from noisy measurements of its support function or its brightness function in $k$ directions $u_1,...,u_k$. The key idea of these algorithms is to construct a…

Statistics Theory · Mathematics 2007-06-13 Richard J. Gardner , Markus Kiderlen , Peyman Milanfar