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Vertex-patch smoothers are essential for the robust convergence of geometric multigrid methods in high-order finite element applications, yet their adoption is traditionally hindered by the prohibitive cost of solving local patch problems.…

Numerical Analysis · Mathematics 2025-12-03 Michał Wichrowski

In this paper a local Fourier analysis for multigrid methods on tetrahedral grids is presented. Different smoothers for the discretization of the Laplace operator by linear finite elements on such grids are analyzed. A four-color smoother…

Numerical Analysis · Computer Science 2014-10-28 B. Gmeiner , T. Gradl , F. Gaspar , U. Rüde

We study smooth stochastic optimization problems on Riemannian manifolds. Via adapting the recently proposed SPIDER algorithm \citep{fang2018spider} (a variance reduced stochastic method) to Riemannian manifold, we can achieve faster rate…

Optimization and Control · Mathematics 2018-12-17 Jingzhao Zhang , Hongyi Zhang , Suvrit Sra

Second-order optimization methods have desirable convergence properties. However, the exact Newton method requires expensive computation for the Hessian and its inverse. In this paper, we propose SPAN, a novel approximate and fast Newton…

Optimization and Control · Mathematics 2020-03-04 Xunpeng Huang , Xianfeng Liang , Zhengyang Liu , Yitan Li , Linyun Yu , Yue Yu , Lei Li

Pseudoinverses are ubiquitous tools for handling over- and under-determined systems of equations. For computational efficiency, sparse pseudoinverses are desirable. Recently, sparse left and right pseudoinverses were introduced, using…

Numerical Analysis · Mathematics 2016-06-23 Victor K. Fuentes , Marcia Fampa , Jon Lee

Three dimensional surface reconstruction based on two dimensional sparse information in the form of only a small number of level lines of the surface with moderately complex structures, containing both structured and unstructured…

Numerical Analysis · Mathematics 2020-09-29 Bin Wu , Xue-Cheng Tai , Talal Rahman

We propose HAMSI (Hessian Approximated Multiple Subsets Iteration), which is a provably convergent, second order incremental algorithm for solving large-scale partially separable optimization problems. The algorithm is based on a local…

In this work, we propose an optimization framework for estimating a sparse robust one-dimensional subspace. Our objective is to minimize both the representation error and the penalty, in terms of the l1-norm criterion. Given that the…

Machine Learning · Statistics 2024-03-07 Xiao Ling , Paul Brooks

This paper proposes a squared smoothing Newton method via the Huber smoothing function for solving semidefinite programming problems (SDPs). We first study the fundamental properties of the matrix-valued mapping defined upon the Huber…

Optimization and Control · Mathematics 2024-10-10 Ling Liang , Defeng Sun , Kim-Chuan Toh

We present a framework for smooth optimization of explicitly regularized objectives for (structured) sparsity. These non-smooth and possibly non-convex problems typically rely on solvers tailored to specific models and regularizers. In…

Machine Learning · Computer Science 2026-04-09 Chris Kolb , Christian L. Müller , Bernd Bischl , David Rügamer

In this paper we propose a new inexact dual decomposition algorithm for solving separable convex optimization problems. This algorithm is a combination of three techniques: dual Lagrangian decomposition, smoothing and excessive gap. The…

Optimization and Control · Mathematics 2013-02-11 Quoc Tran Dinh , Ion Necoara , Moritz Diehl

Approximate Bayesian inference methods that scale to very large datasets are crucial in leveraging probabilistic models for real-world time series. Sparse Markovian Gaussian processes combine the use of inducing variables with efficient…

Machine Learning · Statistics 2021-06-10 William J. Wilkinson , Arno Solin , Vincent Adam

In compressed sensing, the sensing matrix is assumed perfectly known. However, there exists perturbation in the sensing matrix in reality due to sensor offsets or noise disturbance. Directions-of-arrival (DoA) estimation with off-grid…

Signal Processing · Electrical Eng. & Systems 2019-06-04 Cheng-Yu Hung , Mostafa Kaveh

We propose a new fast algorithm for solving one of the standard approaches to ill-posed linear inverse problems (IPLIP), where a (possibly non-smooth) regularizer is minimized under the constraint that the solution explains the observations…

Optimization and Control · Mathematics 2012-10-10 Manya V. Afonso , José M. Bioucas-Dias , Mário A. T. Figueiredo

We aim at the solution of inverse problems in imaging, by combining a penalized sparse representation of image patches with an unconstrained smooth one. This allows for a straightforward interpretation of the reconstruction. We formulate…

Image and Video Processing · Electrical Eng. & Systems 2025-03-18 Stanislas Ducotterd , Sebastian Neumayer , Michael Unser

In this paper we study convergence estimates for a multigrid algorithm with smoothers of successive subspace correction (SSC) type, applied to symmetric elliptic PDEs. First, we revisit a general convergence analysis on a class of multigrid…

Numerical Analysis · Mathematics 2018-05-09 Eugenio Aulisa , Giorgio Bornia , Sara Calandrini , Giacomo Capodaglio

In this paper, we consider two formulations for Linear Matrix Inequalities (LMIs) under Slater type constraint qualification assumption, namely, SDP smooth and non-smooth formulations. We also propose two first-order linearly convergent…

Optimization and Control · Mathematics 2013-09-10 Cong D. Dang , Guanghui Lan

The SPIKE family of linear system solvers provides parallelism using a block tridiagonal partitioning. Typically SPIKE-based solvers are applied to banded systems, resulting in structured off-diagonal blocks with non-zeros elements…

Numerical Analysis · Mathematics 2025-04-16 Braegan S. Spring , Eric Polizzi , Ahmed H. Sameh

In this paper, we propose a simple sparse approximate inverse for triangular matrices (SAIT). Using the Jacobi iteration method, we obtain an expression of the exact inverse of triangular matrix, which is a finite series. The SAIT is…

Numerical Analysis · Mathematics 2021-11-19 Zhongjie Lu

This paper considers smooth convex optimization problems with many functional constraints. To solve this general class of problems we propose a new stochastic perturbed augmented Lagrangian method, called SGDPA, where a perturbation is…

Optimization and Control · Mathematics 2025-04-01 Nitesh Kumar Singh , Ion Necoara