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We present an adaptive algorithm for effectively solving rough differential equations (RDEs) using the log-ODE method. The algorithm is based on an error representation formula that accurately describes the contribution of local errors to…

Numerical Analysis · Mathematics 2023-07-25 Christian Bayer , Simon Breneis , Terry Lyons

We study the computational limits of Low-Rank Adaptation (LoRA) for finetuning transformer-based models using fine-grained complexity theory. Our key observation is that the existence of low-rank decompositions within the gradient…

Machine Learning · Computer Science 2025-06-09 Jerry Yao-Chieh Hu , Maojiang Su , En-Jui Kuo , Zhao Song , Han Liu

In this paper, we implement exponential integrators, specifically Integrating Factor (IF) and Exponential Time Differencing (ETD) methods, using pseudo-spectral techniques to solve phase-field equations within a Python framework. These…

Numerical Analysis · Mathematics 2023-05-17 Elvis do A. Soares , Amaro G. Barreto , Frederico W. Tavares

We consider quadrature formulas of high order in time based on Radau-type, L-stable implicit Runge-Kutta schemes to solve time dependent stiff PDEs. Instead of solving a large nonlinear system of equations, we develop a method that performs…

Numerical Analysis · Mathematics 2016-04-04 Max Duarte , Matthew Emmett

Differential algebraic Riccati equations are at the heart of many applications in control theory. They are time-depent, matrix-valued, and in particular nonlinear equations that require special methods for their solution. Low-rank methods…

Numerical Analysis · Mathematics 2019-12-17 Tobias Breiten , Sergey Dolgov , Martin Stoll

We present a MATLAB toolbox for five different classes of exponential integrators for solving (mildly) stiff ordinary differential equations or time-dependent partial differential equations. For the efficiency of such exponential…

Numerical Analysis · Mathematics 2014-04-18 Georg Jansing

Optimizers like Adam and AdaGrad have been very successful in training large-scale neural networks. Yet, the performance of these methods is heavily dependent on a carefully tuned learning rate schedule. We show that in many large-scale…

Machine Learning · Computer Science 2022-02-02 Ehsan Amid , Rohan Anil , Christopher Fifty , Manfred K. Warmuth

We consider the adaptive-rank integration of {2D and 3D} time-dependent advection-diffusion partial differential equations (PDEs) with variable coefficients. We employ a standard finite-difference method for spatial discretization coupled…

Numerical Analysis · Mathematics 2025-10-02 Hamad El Kahza , Jing-Mei Qiu , Luis Chacon , William Taitano

Parameter-efficient fine-tuning (PEFT) has become a standard approach for adapting large pre-trained models. Amongst PEFT methods, low-rank adaptation (LoRA) has achieved notable success. However, recent studies have highlighted its…

Machine Learning · Computer Science 2025-08-04 Paul Albert , Frederic Z. Zhang , Hemanth Saratchandran , Anton van den Hengel , Ehsan Abbasnejad

In kinetic theory, numerically solving the full Boltzmann equation is extremely expensive. This is because the Boltzmann collision operator involves a high-dimensional, nonlinear integral that must be evaluated at each spatial grid point…

Numerical Analysis · Mathematics 2025-02-14 Lukas Einkemmer , Jingwei Hu , Shiheng Zhang

Phase fitting has been extensively used during the last years to improve the behaviour of numerical integrators on oscillatory problems. In this work, the benefits of the phase fitting technique are embedded in discrete Lagrangian…

Mathematical Physics · Physics 2015-05-13 O. T. Kosmas , D. S. Vlachos

This paper presents a rank-adaptive implicit-explicit integrator for the tensor approximation of three-dimensional convection-diffusion equations. In particular, the recently developed Reduced Augmentation Implicit Low-rank (RAIL)…

Numerical Analysis · Mathematics 2025-08-25 Joseph Nakao , Gianluca Ceruti , Lukas Einkemmer

Dynamical low-rank approximation (DLRA) is a widely used paradigm for solving large-scale matrix differential equations, as they arise, for example, from the discretization of time-dependent partial differential equations on tensorized…

Numerical Analysis · Mathematics 2025-10-23 Benjamin Carrel , Daniel Kressner , Hei Yin Lam , Bart Vandereycken

We introduce an $r-$adaptive algorithm to solve Partial Differential Equations using a Deep Neural Network. The proposed method restricts to tensor product meshes and optimizes the boundary node locations in one dimension, from which we…

Numerical Analysis · Mathematics 2022-10-21 Ángel J. Omella , David Pardo

Efficient simulation of SDEs is essential in many applications, particularly for ergodic systems that demand efficient simulation of both short-time dynamics and large-time statistics. However, locally Lipschitz SDEs often require special…

Numerical Analysis · Mathematics 2021-02-26 Xingjie Li , Fei Lu , Felix X. -F. Ye

This paper proposes a new framework for computing low-rank solutions to nonlinear matrix equations arising from spatial discretization of nonlinear partial differential equations: low-rank Anderson acceleration (lrAA). lrAA is an adaptation…

Numerical Analysis · Mathematics 2025-03-25 Daniel Appelo , Yingda Cheng

Continuous-time algebraic Riccati equations can be found in many disciplines in different forms. In the case of small-scale dense coefficient matrices, stabilizing solutions can be computed to all possible formulations of the Riccati…

Numerical Analysis · Mathematics 2024-09-18 Jens Saak , Steffen W. R. Werner

Differentiable systems in this paper means systems of equations that are described by differentiable real functions in real matrix variables. This paper proposes algorithms for finding minimal rank solutions to such systems over (arbitrary…

Optimization and Control · Mathematics 2017-05-30 Thanh Hieu Le

Error estimates for the numerical solution of the master equation are presented. Estimates are based on adjoint methods. We find that a good estimate can often be computed without spending computational effort on a dual problem. Estimates…

Numerical Analysis · Mathematics 2016-10-12 Katharina Kormann , Shev MacNamara

Starting from a recent a posteriori error estimator for the finite element solution of the wave equation with explicit time-stepping [Grote, Lakkis, Santos, 2024], we devise a space-time adaptive strategy which includes both time evolving…

Numerical Analysis · Mathematics 2026-01-07 Marcus J. Grote , Omar Lakkis , Carina S. Santos