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Fault tolerant algorithms for the numerical approximation of elliptic partial differential equations on modern supercomputers play a more and more important role in the future design of exa-scale enabled iterative solvers. Here, we combine…

Mathematical Software · Computer Science 2015-06-23 Markus Huber , Björn Gmeiner , Ulrich Rüde , Barbara Wohlmuth

As CPU clock speeds have stagnated and high performance computers continue to have ever higher core counts, increased parallelism is needed to take advantage of these new architectures. Traditional serial time-marching schemes can be a…

Numerical Analysis · Mathematics 2022-08-29 David A. Vargas , Robert D. Falgout , Stefanie Günther , Jacob B. Schroder

The multigrid algorithm is an efficient numerical method for solving a variety of elliptic partial differential equations (PDEs). The method damps errors at progressively finer grid scales, resulting in faster convergence compared to…

Numerical Analysis · Mathematics 2021-05-06 Francisco Holguin , GS Sidharth , Gavin Portwood

Algebraic multigrid (AMG) is often an effective solver for symmetric positive definite (SPD) linear systems resulting from the discretization of general elliptic PDEs, or the spatial discretization of parabolic PDEs. However, convergence…

Numerical Analysis · Mathematics 2019-09-10 Thomas A. Manteuffel , Steffen Munzenmaier , John Ruge , Ben S. Southworth

Method for a mosaic image representation (MIR) is proposed for a selective treatment of image fragments of different transition frequency. MIR method is based on piecewise-constant image approximation on a non-uniform orthogonal grid…

Data Analysis, Statistics and Probability · Physics 2011-03-14 Evgenia Gelman

This paper proposes the Proximal Iteratively REweighted (PIRE) algorithm for solving a general problem, which involves a large body of nonconvex sparse and structured sparse related problems. Comparing with previous iterative solvers for…

Numerical Analysis · Computer Science 2014-04-29 Canyi Lu , Yunchao Wei , Zhouchen Lin , Shuicheng Yan

Image restoration is a typical ill-posed problem, and it contains various tasks. In the medical imaging field, an ill-posed image interrupts diagnosis and even following image processing. Both traditional iterative and up-to-date deep…

Image and Video Processing · Electrical Eng. & Systems 2021-02-12 Moran Xu , Dianlin Hu , Weifei Wu , Weiwen Wu

We present a novel iterative scheme for restoring uneven illumination in grayscale images. Our approach solves, at each global iteration, a nonlinear elliptic equation for an auxiliary field $u$ and then updates the illumination via an…

Analysis of PDEs · Mathematics 2025-06-17 Dragos-Patru Covei

Existing manifold learning methods are not appropriate for image retrieval task, because most of them are unable to process query image and they have much additional computational cost especially for large scale database. Therefore, we…

Computer Vision and Pattern Recognition · Computer Science 2018-04-04 Jian Xu , Chunheng Wang , Chengzuo Qi , Cunzhao Shi , Baihua Xiao

Due to its optimal complexity, the multigrid (MG) method is one of the most popular approaches for solving large-scale linear systems arising from the discretization of partial differential equations. However, the parallel implementation of…

Numerical Analysis · Mathematics 2025-02-27 Hardik Kothari , Maria Giuseppina Chiara Nestola , Marco Favino , Rolf Krause

Ptychography is a powerful imaging technique that is used in a variety of fields, including materials science, biology, and nanotechnology. However, the accuracy of the reconstructed ptychography image is highly dependent on the accuracy of…

Applied Physics · Physics 2024-06-03 Ming Du , Tao Zhou , Junjing Deng , Daniel J. Ching , Steven Henke , Mathew J. Cherukara

This paper proposes a new framework to regularize the highly ill-posed and non-linear phase retrieval problem through deep generative priors using simple gradient descent algorithm. We experimentally show effectiveness of proposed algorithm…

Machine Learning · Computer Science 2018-08-20 Fahad Shamshad , Ali Ahmed

High-fidelity numerical simulations of chaotic, high dimensional nonlinear dynamical systems are computationally expensive, necessitating the development of efficient surrogate models. Most surrogate models for such systems are…

Machine Learning · Computer Science 2026-03-16 Dibyajyoti Chakraborty , Hojin Kim , Romit Maulik

A long-standing challenge in tomography is the 'missing wedge' problem, which arises when the acquisition of projection images within a certain angular range is restricted due to geometrical constraints. This incomplete dataset results in…

Materials Science · Physics 2025-03-26 Chonghang Zhao , Mingyuan Ge , Xiaogang Yang , Yong S. Chu , Hanfei Yan

Reconstruction of signals from compressively sensed measurements is an ill-posed problem. In this paper, we leverage the recurrent generative model, RIDE, as an image prior for compressive image reconstruction. Recurrent networks can model…

Computer Vision and Pattern Recognition · Computer Science 2017-05-05 Akshat Dave , Anil Kumar Vadathya , Kaushik Mitra

The geometric multigrid algorithm is an efficient numerical method for solving a variety of elliptic partial differential equations (PDEs). The method damps errors at progressively finer grid scales, resulting in faster convergence compared…

Numerical Analysis · Mathematics 2024-03-14 Francisco Holguin , GS Sidharth , Gavin Portwood

Embedding parameterized optimization problems as layers into machine learning architectures serves as a powerful inductive bias. Training such architectures with stochastic gradient descent requires care, as degenerate derivatives of the…

Machine Learning · Computer Science 2024-12-16 Anselm Paulus , Georg Martius , Vít Musil

Multimodal Retrieval-Augmented Generation (Visual RAG) significantly advances question answering by integrating visual and textual evidence. Yet, current evaluations fail to systematically account for query difficulty and ambiguity. We…

Computation and Language · Computer Science 2026-01-14 Yuelyu Ji , Wuwei Lan , Patrick NG

In image reconstruction, an accurate quantification of uncertainty is of great importance for informed decision making. Here, the Bayesian approach to inverse problems can be used: the image is represented through a random function that…

Numerical Analysis · Mathematics 2025-04-24 Jonas Latz , Aretha L. Teckentrup , Simon Urbainczyk

Intrinsic image decomposition is the process of recovering the image formation components (reflectance and shading) from an image. Previous methods employ either explicit priors to constrain the problem or implicit constraints as formulated…

Computer Vision and Pattern Recognition · Computer Science 2022-05-03 Partha Das , Sezer Karaoglu , Theo Gevers
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