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Electrical Impedance Tomography (EIT) is a non-invasive medical imaging method that reconstructs electrical conductivity mediums from boundary voltage-current measurements, but its severe ill-posedness renders direct operator learning with…

Numerical Analysis · Mathematics 2026-01-14 Amit Bhat , Ke Chen , Chunmei Wang

This paper introduces a factorization for the inverse of discrete Fourier integral operators that can be applied in quasi-linear time. The factorization starts by approximating the operator with the butterfly factorization. Next, a…

Numerical Analysis · Mathematics 2021-09-15 Jordi Feliu-Fabà , Lexing Ying

In this work, we propose and study a framework of generalized proximal point algorithms associated with a maximally monotone operator. We indicate sufficient conditions on the regularization and relaxation parameters of generalized proximal…

Optimization and Control · Mathematics 2022-03-29 Hui Ouyang

Standard regularization methods typically favor solutions which are in, or close to, the orthogonal complement of the null space of the forward operator/matrix $\mathsf{A}$. This particular biasedness might not be desirable in applications…

Numerical Analysis · Mathematics 2025-09-05 Ole Løseth Elvetun , Bjørn Fredrik Nielsen , Niranjana Sudheer

Proximal operators are now ubiquitous in non-smooth optimization. Since their introduction in the seminal work of Moreau, many papers have shown their effectiveness on a wide variety of problems, culminating in their use to construct…

Optimization and Control · Mathematics 2026-02-03 Guillaume Lauga , Samuel Vaiter

Fusion frames have become a major tool in the implementation of distributed systems. The effectiveness of fusion frame applications in distributed systems is reflected in the efficiency of the end fusion process. This in turn is reflected…

Functional Analysis · Mathematics 2010-12-08 Jameson Cahill , Peter Casazza , Shidong Li

Let $S\in\mathcal{M}_d(\mathbb{C})^+$ be a positive semidefinite $d\times d$ complex matrix and let $\mathbf a=(a_i)_{i\in\mathbb{I}_k}\in \mathbb{R}_{>0}^k$, indexed by $\mathbb{I}_k=\{1,\ldots,k\}$, be a $k$-tuple of positive numbers. Let…

Functional Analysis · Mathematics 2018-12-27 Pedro Massey , Noelia Rios , Demetrio Stojanoff

Frames formed by orbits of vectors through the iteration of a bounded operator have recently attracted considerable attention, in particular due to its applications to dynamical sampling. In this article, we consider two commuting bounded…

Functional Analysis · Mathematics 2023-05-18 A. Aguilera , C. Cabrelli , D. Carbajal , V. Paternostro

Proper splittings of operators are commonly used to study the convergence of iterative processes. In order to approximate solutions of operator equations, in this article we deal with proper splittings of closed range bounded linear…

Functional Analysis · Mathematics 2024-03-18 Guillermina Fongi , María Celeste Gonzalez

We study approximate Birkhoff-James orthogonality of bounded linear operators defined between normed linear spaces $\mathbb{X}$ and $\mathbb{Y}.$ As an application of the results obtained, we characterize smoothness of a bounded linear…

Functional Analysis · Mathematics 2024-08-13 Arpita Mal , Kallol Paul , T. S. S. R. K. Rao , Debmalya Sain

This paper deals with the possibility of transforming a weakly measurable function in a Hilbert space into a continuous frame by a metric operator, i.e., a strictly positive self-adjoint operator. A necessary condition is that the domain of…

Functional Analysis · Mathematics 2020-02-27 J-P. Antoine , R. Corso , C. Trapani

Operator convex functions defined on the positive half-line play a prominent role in the theory of quantum information, where they are used to define quantum $f$-divergences. Such functions admit integral representations in terms of…

Optimization and Control · Mathematics 2023-05-23 Oisín Faust , Hamza Fawzi

Proximal point algorithm has found many applications, and it has been playing fundamental roles in the understanding, design, and analysis of many first-order methods. In this paper, we derive the tight convergence rate in subgradient norm…

Optimization and Control · Mathematics 2023-01-10 Guoyong Gu , Junfeng Yang

Proximal algorithms have gained popularity in recent years in large-scale and distributed optimization problems. One such problem is the phase retrieval problem, for which proximal operators have been proposed recently. The phase retrieval…

Optimization and Control · Mathematics 2018-08-16 Biel Roig-Solvas , Lee Makowski , Dana H. Brooks

In this article we discuss the convergence of first order operators on a thickened graph (a graph-like space) towards a similar operator on the underlying metric graph. On the graph-like space, the first order operator is of the form…

Mathematical Physics · Physics 2025-07-24 Pavel Exner , Olaf Post

The purpose of the paper is to analyze frames $\{f_k\}_{k\in \mathbf Z}$ having the form $\{T^kf_0\}_{k\in\mathbf Z}$ for some linear operator $T: \mbox{span} \{f_k\}_{k\in \mathbf Z} \to \mbox{span}\{f_k\}_{k\in \mathbf Z}$. A key result…

Functional Analysis · Mathematics 2017-05-01 Ole Christensen , Marzieh Hasannasab

The three operator splitting scheme was recently proposed by [Davis and Yin, 2015] as a method to optimize composite objective functions with one convex smooth term and two convex (possibly non-smooth) terms for which we have access to…

Machine Learning · Statistics 2021-06-29 Fabian Pedregosa

Soft threshold pruning is among the cutting-edge pruning methods with state-of-the-art performance. However, previous methods either perform aimless searching on the threshold scheduler or simply set the threshold trainable, lacking…

Machine Learning · Computer Science 2023-02-28 Yanqi Chen , Zhengyu Ma , Wei Fang , Xiawu Zheng , Zhaofei Yu , Yonghong Tian

The explicit split-operator algorithm is often used for solving the linear and nonlinear time-dependent Schr\"{o}dinger equations. However, when applied to certain nonlinear time-dependent Schr\"{o}dinger equations, this algorithm loses…

Chemical Physics · Physics 2024-09-26 Julien Roulet , Jiří Vaníček

The computational cost of many signal processing and machine learning techniques is often dominated by the cost of applying certain linear operators to high-dimensional vectors. This paper introduces an algorithm aimed at reducing the…

Machine Learning · Computer Science 2016-03-30 Luc Le Magoarou , Rémi Gribonval