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Randomized linear system solvers have become popular as they have the potential to reduce floating point complexity while still achieving desirable convergence rates. One particularly promising class of methods, random sketching solvers,…

Numerical Analysis · Mathematics 2020-12-23 Vivak Patel , Mohammad Jahangoshahi , Daniel Adrian Maldonado

In this paper, we have established a new framework of truncated inverse sampling for estimating mean values of non-negative random variables such as binomial, Poisson, hyper-geometrical, and bounded variables. We have derived explicit…

Statistics Theory · Mathematics 2013-11-05 Xinjia Chen

Undersampling the k-space in MRI allows saving precious acquisition time, yet results in an ill-posed inversion problem. Recently, many deep learning techniques have been developed, addressing this issue of recovering the fully sampled MR…

Image and Video Processing · Electrical Eng. & Systems 2020-07-28 Mélanie Gaillochet , Kerem C. Tezcan , Ender Konukoglu

In computational inverse problems, it is common that a detailed and accurate forward model is approximated by a computationally less challenging substitute. The model reduction may be necessary to meet constraints in computing time when…

Methodology · Statistics 2018-02-14 Daniela Calvetti , Matthew M. Dunlop , Erkki Somersalo , Andrew M. Stuart

Scalable algorithms to solve optimization and regression tasks even approximately, are needed to work with large datasets. In this paper we study efficient techniques from matrix sketching to solve a variety of convex constrained regression…

Machine Learning · Computer Science 2019-11-01 Graham Cormode , Charlie Dickens

We consider minimizing finite-sum and expectation objective functions via Hessian-averaging based subsampled Newton methods. These methods allow for gradient inexactness and have fixed per-iteration Hessian approximation costs. The recent…

Optimization and Control · Mathematics 2024-08-15 Thomas O'Leary-Roseberry , Raghu Bollapragada

The randomized version of the Kaczmarz method for the solution of linear systems is known to converge linearly in expectation. In this work we extend this result and show that the recently proposed Randomized Sparse Kaczmarz method for…

Optimization and Control · Mathematics 2016-10-11 Frank Schöpfer , Dirk A. Lorenz

The traditional approach of hand-crafting priors (such as sparsity) for solving inverse problems is slowly being replaced by the use of richer learned priors (such as those modeled by deep generative networks). In this work, we study the…

Machine Learning · Computer Science 2021-05-14 Viraj Shah , Rakib Hyder , M. Salman Asif , Chinmay Hegde

There is an increasing body of work exploring the integration of random projection into algorithms for numerical linear algebra. The primary motivation is to reduce the overall computational cost of processing large datasets. A suitably…

Numerical Analysis · Mathematics 2022-01-04 Daniel Ahfock , William J. Astle , Sylvia Richardson

This work presents an approach to the inverse design of scattering systems by modifying the transmission matrix using reinforcement learning. We utilize Proximal Policy Optimization to navigate the highly non-convex landscape of the object…

Optics · Physics 2025-06-17 Yuhao Kang

Blind inverse problems arise in many experimental settings where both the signal of interest and the forward operator are (partially) unknown. In this context, methods developed for the non-blind case cannot be adapted in a straightforward…

Machine Learning · Computer Science 2026-04-21 Nathan Buskulic , Luca Calatroni , Lorenzo Rosasco , Silvia Villa

Many imaging technologies rely on tomographic reconstruction, which requires solving a multidimensional inverse problem given a finite number of projections. Backprojection is a popular class of algorithm for tomographic reconstruction,…

Image and Video Processing · Electrical Eng. & Systems 2020-06-03 Xueqing Liu , Paul Sajda

Undersampling the k-space during MR acquisitions saves time, however results in an ill-posed inversion problem, leading to an infinite set of images as possible solutions. Traditionally, this is tackled as a reconstruction problem by…

Image and Video Processing · Electrical Eng. & Systems 2022-02-10 Kerem C. Tezcan , Neerav Karani , Christian F. Baumgartner , Ender Konukoglu

We present a likelihood-free probabilistic inversion method based on normalizing flows for high-dimensional inverse problems. The proposed method is composed of two complementary networks: a summary network for data compression and an…

Machine Learning · Computer Science 2024-12-30 Jice Zeng , Yuanzhe Wang , Alexandre M. Tartakovsky , David Barajas-Solano

In order to solve tasks like uncertainty quantification or hypothesis tests in Bayesian imaging inverse problems, we often have to draw samples from the arising posterior distribution. For the usually log-concave but high-dimensional…

Computation · Statistics 2025-01-23 Matthias J. Ehrhardt , Lorenz Kuger , Carola-Bibiane Schönlieb

We examine a class of embeddings based on structured random matrices with orthogonal rows which can be applied in many machine learning applications including dimensionality reduction and kernel approximation. For both the…

Machine Learning · Statistics 2018-09-05 Krzysztof Choromanski , Mark Rowland , Adrian Weller

We reconsider randomized algorithms for the low-rank approximation of symmetric positive semi-definite (SPSD) matrices such as Laplacian and kernel matrices that arise in data analysis and machine learning applications. Our main results…

Machine Learning · Computer Science 2013-06-05 Alex Gittens , Michael W. Mahoney

Bayesian deep learning counts on the quality of posterior distribution estimation. However, the posterior of deep neural networks is highly multi-modal in nature, with local modes exhibiting varying generalization performance. Given a…

Machine Learning · Computer Science 2024-03-27 Bolian Li , Ruqi Zhang

Supervised convolutional neural networks (CNNs) are widely used to solve imaging inverse problems, achieving state-of-the-art performance in numerous applications. However, despite their empirical success, these methods are poorly…

Computer Vision and Pattern Recognition · Computer Science 2026-05-28 Minh Hai Nguyen , Quoc Bao Do , Edouard Pauwels , Pierre Weiss

Due to the limited number of bits in floating-point or fixed-point arithmetic, rounding is a necessary step in many computations. Although rounding methods can be tailored for different applications, round-off errors are generally…

Numerical Analysis · Mathematics 2020-06-02 Lu Xia , Martijn Anthonissen , Michiel Hochstenbach , Barry Koren