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Iterative solvers for large-scale linear systems such as Krylov subspace methods can diverge when the linear system is ill-conditioned, thus significantly reducing the applicability of these iterative methods in practice for…

Numerical Analysis · Mathematics 2025-07-24 Vasileios Kalantzis , Mark S. Squillante , Chai Wah Wu

When solving rank-deficient or discrete ill-posed problems by regularization methods, the choice of the regularization parameter is crucial. It is also of interest, the regularization norm used in the selection of the solution. In this…

Numerical Analysis · Mathematics 2024-10-30 Ibrahima Dione

We investigate a level-set type method for solving ill-posed problems, with the assumption that the solutions are piecewise, but not necessarily constant functions with unknown level sets and unknown level values. In order to get stable…

Numerical Analysis · Mathematics 2012-10-30 Adriano De Cezaro

We investigate iterated Tikhonov methods coupled with a Kaczmarz strategy for obtaining stable solutions of nonlinear systems of ill-posed operator equations. We show that the proposed method is a convergent regularization method. In the…

Numerical Analysis · Mathematics 2020-12-23 J. Baumeister , A. De Cezaro , A. Leitao

This paper considers the inversion of ill-posed linear operators. To regularise the problem the solution is enforced to lie in a non-convex subset. Theoretical properties for the stable inversion are derived and an iterative algorithm akin…

Numerical Analysis · Mathematics 2009-11-30 Thomas Blumensath

Tikhonov regularization is one of the most commonly used methods of regularization of ill-posed problems. In the setting of finite element solutions of elliptic partial differential control problems, Tikhonov regularization amounts to…

Numerical Analysis · Mathematics 2016-09-19 Erik Burman , Peter Hansbo , Mats Larson

This paper surveys an important class of methods that combine iterative projection methods and variational regularization methods for large-scale inverse problems. Iterative methods such as Krylov subspace methods are invaluable in the…

Numerical Analysis · Mathematics 2021-08-23 Julianne Chung , Silvia Gazzola

In this paper we consider new regularization methods for linear inverse problems of dynamic type. These methods are based on dynamic programming techniques for linear quadratic optimal control problems. Two different approaches are…

Numerical Analysis · Mathematics 2021-01-26 S. Kindermann , A. Leitao

We consider the problem of designing efficient regularization algorithms when regularization is encoded by a (strongly) convex functional. Unlike classical penalization methods based on a relaxation approach, we propose an iterative method…

Optimization and Control · Mathematics 2017-07-19 Simon Matet , Lorenzo Rosasco , Silvia Villa , Bang Long Vu

Connected with the rise of interest in inverse problems is the development and analysis of regularization methods, which are a necessity due to the ill-posedness of inverse problems. Tikhonov-type regularization methods are very popular in…

Numerical Analysis · Mathematics 2021-03-16 Abinash Nayak

We investigate modified steepest descent methods coupled with a loping Kaczmarz strategy for obtaining stable solutions of nonlinear systems of ill-posed operator equations. We show that the proposed method is a convergent regularization…

Numerical Analysis · Mathematics 2008-08-03 A. De Cezaro , M. Haltmeier , A. Leitao , O. Scherzer

Various versions of the Dynamical Systems Method (DSM) are proposed for solving linear ill-posed problems with bounded and unbounded operators. Convergence of the proposed methods is proved. Some new results concerning discrepancy principle…

Numerical Analysis · Mathematics 2007-05-23 A. G. Ramm

A new method, the Dynamical Systems Method (DSM), justified recently, is applied to solving ill-conditioned linear algebraic system (ICLAS). The DSM gives a new approach to solving a wide class of ill-posed problems. In this paper a new…

Numerical Analysis · Mathematics 2009-12-04 Sapto W. Indratno , A. G. Ramm

The problem of numerical differentiation can be thought of as an inverse problem by considering it as solving a Volterra equation. It is well known that such inverse integral problems are ill-posed and one requires regularization methods to…

Numerical Analysis · Mathematics 2020-04-15 Abinash Nayak

Inverse problems arise in a wide spectrum of applications in fields ranging from engineering to scientific computation. Connected with the rise of interest in inverse problems is the development and analysis of regularization methods, such…

Numerical Analysis · Mathematics 2025-05-12 Abinash Nayak

We derive and analyse a new variant of the iteratively regularized Landweber iteration, for solving linear and nonlinear ill-posed inverse problems. The method takes into account training data, which are used to estimate the interior of a…

Numerical Analysis · Mathematics 2020-03-19 Andrea Aspri , Sebastian Banert , Ozan Öktem , Otmar Scherzer

It's well-known that inverse problems are ill-posed and to solve them meaningfully one has to employ regularization methods. Traditionally, popular regularization methods have been the penalized Variational approaches. In recent years, the…

Machine Learning · Computer Science 2022-02-17 Abinash Nayak

In this article, we introduce and study accelerated Landweber methods for linear ill-posed problems obtained by an alteration of the coefficients in the three-term recurrence relation of the \nu-methods. The residual polynomials of the…

Numerical Analysis · Mathematics 2012-12-21 Wolfgang Erb

We study iterative regularization for linear models, when the bias is convex but not necessarily strongly convex. We characterize the stability properties of a primal-dual gradient based approach, analyzing its convergence in the presence…

Machine Learning · Statistics 2020-10-30 Cesare Molinari , Mathurin Massias , Lorenzo Rosasco , Silvia Villa

Image restoration refers to the process of reconstructing noisy, destroyed, or missing parts of an image, which is an ill-posed inverse problem. A specific regularization term and image degradation are typically assumed to achieve…

Image and Video Processing · Electrical Eng. & Systems 2025-04-15 Jianwei Ke