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Random projections offer an appealing and flexible approach to a wide range of large-scale statistical problems. They are particularly useful in high-dimensional settings, where we have many covariates recorded for each observation. In…

Methodology · Statistics 2019-11-26 Timothy I. Cannings

We focus on the optimization problem with smooth, possibly nonconvex objectives and a convex constraint set for which the Euclidean projection operation is practically available. Focusing on this setting, we carry out a general convergence…

Optimization and Control · Mathematics 2026-04-23 Matteo Lapucci , Giampaolo Liuzzi , Stefano Lucidi , Marco Sciandrone , Diego Scuppa

We describe a procedure to compute a projection of $w \in \mathbb{R}^n$ into the intersection of the so-called \emph{zero-norm} ball $k \mathbb{B}_0$ of radius $k$, i.e., the set of $k$-sparse vectors, with a box centered at a point of $k…

Optimization and Control · Mathematics 2022-04-13 Dominique Orban

Objective: In this work, we propose a framework for differentiable forward and back-projector that enables scalable, accurate, and memory-efficient gradient computation for rigid motion estimation tasks. Methods: Unlike existing approaches…

Medical Physics · Physics 2025-12-16 Xiao Jiang , Xin Wang , Ali Uneri , Wojciech B. Zbijewski , J. Webster Stayman

In this note, we present a new averaging technique for the projected stochastic subgradient method. By using a weighted average with a weight of t+1 for each iterate w_t at iteration t, we obtain the convergence rate of O(1/t) with both an…

Machine Learning · Computer Science 2012-12-21 Simon Lacoste-Julien , Mark Schmidt , Francis Bach

Fast Fourier transforms are used to develop algorithms for the fast generation of correlated Gaussian random fields on d-dimensional rectangular regions. The complexities of the algorithms are derived, simulation results and error analysis…

Numerical Analysis · Mathematics 2013-07-19 Annika Lang , Jürgen Potthoff

This paper proposes a polyline shaped array based system scheme, associated with mechanical scanning along the perpendicular direction of the array, for near-field millimeter-wave (MMW) imaging. Each section of the polyline is a chord of a…

Signal Processing · Electrical Eng. & Systems 2021-09-08 Shuoguang Wang , Shiyong Li , Guoqiang Zhao , Houjun Sun

In this paper, we provide a finitely terminated yet efficient approach to compute the Euclidean projection onto the ordered weighted $\ell_1$ (OWL1) norm ball. In particular, an efficient semismooth Newton method is proposed for solving the…

Optimization and Control · Mathematics 2020-07-21 Qinzhen Li , Xudong Li

To measure the similarity of documents, the Wasserstein distance is a powerful tool, but it requires a high computational cost. Recently, for fast computation of the Wasserstein distance, methods for approximating the Wasserstein distance…

Machine Learning · Computer Science 2021-07-26 Yuki Takezawa , Ryoma Sato , Makoto Yamada

We propose a fast and scalable variational method for Bayesian inference in high-dimensional parameter space, which we call projected Stein variational Newton (pSVN) method. We exploit the intrinsic low-dimensional geometric structure of…

Optimization and Control · Mathematics 2020-02-11 Peng Chen , Keyi Wu , Joshua Chen , Thomas O'Leary-Roseberry , Omar Ghattas

This project is aimed at designing the fast forward projection algorithm and also the backprojection algorithm for cone beam CT imaging systems with circular X-ray source trajectory. The principle of the designs is based on utilizing the…

Data Structures and Algorithms · Computer Science 2016-05-18 Junqi Tang

Image projection through scattering media has applications ranging from light delivery through multimode fiber to near-eye displays. Conventional methods utilize the transmission matrix (TM) measured by interfering with a reference beam.…

Inspired by recent work on extended image volumes that lays the ground for randomized probing of extremely large seismic wavefield matrices, we present a memory frugal and computationally efficient inversion methodology that uses techniques…

Geophysics · Physics 2021-04-05 Mathias Louboutin , Felix J. Herrmann

We construct and analyze a projection-free linearly implicit method for the approximation of flows of harmonic maps into spheres. The proposed method is unconditionally energy stable and, under a sharp discrete regularity condition,…

Numerical Analysis · Mathematics 2026-02-16 Georgios Akrivis , Sören Bartels , Michele Ruggeri , Jilu Wang

Numerical simulation of complex optical structures enables their optimization with respect to specific objectives. Often, optimization is done by multiple successive parameter scans, which are time consuming and computationally expensive.…

Computational Physics · Physics 2017-07-27 P. -I. Schneider , X. Garcia Santiago , C. Rockstuhl , S. Burger

We present a fast algorithm for evaluating the (non-smooth) solution of the free-space two-dimensional (2D) scalar wave equation with many point sources, each with a high-frequency band-limited time signature. Such an algorithm is key to an…

Numerical Analysis · Mathematics 2026-04-09 Nour G. Al Hassanieh , Leslie Greengard , Alex H. Barnett

We consider a troublesome form of non-isoplanatism in synthesis radio telescopes: non-coplanar baselines. We present a novel interpretation of the non-coplanar baselines effect as being due to differential Fresnel diffraction in the…

Astrophysics · Physics 2009-11-13 T. J. Cornwell , K. Golap , S. Bhatnagar

Sparse variational approximations are popular methods for scaling up inference and learning in Gaussian processes to larger datasets. For $N$ training points, exact inference has $O(N^3)$ cost; with $M \ll N$ features, state of the art…

Machine Learning · Statistics 2024-04-15 Talay M Cheema , Carl Edward Rasmussen

We propose a projected Wasserstein gradient descent method (pWGD) for high-dimensional Bayesian inference problems. The underlying density function of a particle system of WGD is approximated by kernel density estimation (KDE), which faces…

Machine Learning · Computer Science 2021-02-16 Yifei Wang , Peng Chen , Wuchen Li

Gromov--Wasserstein optimal transport (GWOT) aligns metric measure spaces by matching their within-domain relational structures, but large-scale GWOT remains challenging because its objective is nonconvex and projection onto the transport…

Machine Learning · Computer Science 2026-05-07 Ling Liang , Lei Yang