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This paper proposes a mode multigrid (MMG) method, and applies it to accelerate the convergence of the steady state flow on unstructured grids. The dynamic mode decomposition (DMD) technique is used to analyze the convergence process of…

Computational Physics · Physics 2018-02-27 Yilang Liu , Weiwei Zhang , Jiaqing Kou

Brain encoding with neuroimaging data is an established analysis aimed at predicting human brain activity directly from complex stimuli features such as movie frames. Typically, these features are the latent space representation from an…

Machine Learning · Computer Science 2024-03-29 Sana Ahmadi , Pierre Bellec , Tristan Glatard

The simulation of systems that act on multiple time scales is challenging. A stable integration of the fast dynamics requires a highly accurate approximation whereas for the simulation of the slow part, a coarser approximation is accurate…

Numerical Analysis · Mathematics 2024-06-21 Sina Ober-Blöbaum , Theresa Wenger , Tobias Gail , Sigrid Leyendecker

A space-time adaptive scheme is presented for solving advection equations in two space dimensions. The gradient-augmented level set method using a semi-Lagrangian formulation with backward time integration is coupled with a point value…

Computational Physics · Physics 2015-04-20 Dmitry Kolomenskiy , Jean-Christophe Nave , Kai Schneider

Parallel-in-time algorithms have been successfully employed for reducing time-to-solution of a variety of partial differential equations, especially for diffusive (parabolic-type) equations. A major failing of parallel-in-time approaches to…

Numerical Analysis · Mathematics 2019-08-28 Hans De Sterck , Stephanie Friedhoff , Alexander J. M. Howse , Scott P. MacLachlan

Motivated by broad applications in machine learning, we study the popular accelerated stochastic gradient descent (ASGD) algorithm for solving (possibly nonconvex) optimization problems. We characterize the finite-time performance of this…

Optimization and Control · Mathematics 2020-10-20 Thinh T. Doan , Lam M. Nguyen , Nhan H. Pham , Justin Romberg

There has been significant progress in understanding the parallelism inherent to iterative sequential algorithms: for many classic algorithms, the depth of the dependence structure is now well understood, and scheduling techniques have been…

Data Structures and Algorithms · Computer Science 2018-08-14 Dan Alistarh , Trevor Brown , Justin Kopinsky , Giorgi Nadiradze

Stochastic Gradient Langevin Dynamics (SGLD) ensures strong guarantees with regards to convergence in measure for sampling log-concave posterior distributions by adding noise to stochastic gradient iterates. Given the size of many practical…

Machine Learning · Computer Science 2020-06-15 Vyacheslav Kungurtsev , Bapi Chatterjee , Dan Alistarh

This paper proposes a metric for sets of trajectories to evaluate multi-object tracking algorithms that includes time-weighted costs for localisation errors of properly detected targets, for false targets, missed targets and track switches.…

Computer Vision and Pattern Recognition · Computer Science 2021-10-27 Ángel F. García-Fernández , Abu Sajana Rahmathullah , Lennart Svensson

Large-scale machine learning models are trained on clusters of machines that exhibit heterogeneous performance due to hardware variability, network delays, and system-level instabilities. In such environments, time complexity rather than…

Optimization and Control · Mathematics 2026-05-12 Zhirayr Tovmasyan , Artavazd Maranjyan , Peter Richtárik

We investigate the problem of minimizing the expectation of smooth nonconvex functions in a distributed setting with multiple parallel workers that are able to compute stochastic gradients. A significant challenge in this context is the…

Optimization and Control · Mathematics 2025-06-16 Artavazd Maranjyan , Omar Shaikh Omar , Peter Richtárik

In this work, we propose an efficient and robust multigrid method for solving the time-fractional heat equation. Due to the nonlocal property of fractional differential operators, numerical methods usually generate systems of equations for…

Numerical Analysis · Mathematics 2017-08-28 Francisco J. Gaspar , Carmen Rodrigo

MGARD (MultiGrid Adaptive Reduction of Data) is an algorithm for compressing and refactoring scientific data, based on the theory of multigrid methods. The core algorithm is built around stable multilevel decompositions of conforming…

Numerical Analysis · Mathematics 2024-12-16 Viktor Reshniak , Evan Ferguson , Qian Gong , Nicolas Vidal , Rick Archibald , Scott Klasky

This paper studies the scheduling of a large population of non-preemptive flexible electric loads, each of which has a flexible starting time but once started will follow a fixed load shape until completion. We first formulate the…

Optimization and Control · Mathematics 2025-03-10 Mehdi Davoudi , Mingyu Chen , Junjie Qin

Stochastic gradient descent (SGD) algorithm and its variations have been effectively used to optimize neural network models. However, with the rapid growth of big data and deep learning, SGD is no longer the most suitable choice due to its…

Machine Learning · Computer Science 2024-02-13 Anuraganand Sharma

We present and analyze for a scalar linear evolution model problem a time multigrid algorithm for DG-discretizations in time. We derive asymptotically optimized parameters for the smoother, and also an asymptotically sharp convergence…

Numerical Analysis · Mathematics 2014-10-02 Martin J. Gander , Martin Neumüller

Algebraic multigrid (AMG) is one of the most widely used solution techniques for linear systems of equations arising from discretized partial differential equations. The popularity of AMG stems from its potential to solve linear systems in…

Numerical Analysis · Mathematics 2026-04-03 Carlo Janna , Andrea Franceschini , Jacob B. Schroder , Luke Olson

Iterative linear solvers have gained recent popularity due to their computational efficiency and low memory footprint for large-scale linear systems. The relaxation method, or Motzkin's method, can be viewed as an iterative method that…

Numerical Analysis · Mathematics 2018-10-30 Jamie Haddock , Deanna Needell

We introduce GRiD: a GPU-accelerated library for computing rigid body dynamics with analytical gradients. GRiD was designed to accelerate the nonlinear trajectory optimization subproblem used in state-of-the-art robotic planning, control,…

Robotics · Computer Science 2023-03-03 Brian Plancher , Sabrina M. Neuman , Radhika Ghosal , Scott Kuindersma , Vijay Janapa Reddi

In this work we present two new families of multirate time step adaptivity controllers, that are designed to work with embedded multirate infinitesimal (MRI) time integration methods for adapting time steps when solving problems with…

Numerical Analysis · Mathematics 2026-03-11 Daniel R. Reynolds , Sylvia Amihere , Dashon Mitchell , Vu Thai Luan