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Sébastien Loisel

Publications and source records attributed to Sébastien Loisel.

3 recordsLinked to original sources
arXiv2023

Algorithm MGB to solve highly nonlinear elliptic PDEs in $\tilde{O}(n)$ FLOPS

We introduce Algorithm MGB (Multi Grid Barrier) for solving highly nonlinear convex Euler-Lagrange equations. This class of problems includes many highly nonlinear partial differential equations, such as $p$-Laplacians. We prove that, if certain regularity hypotheses are satisfied, then our algorithm converges in $\tilde{O}(1)$ damped Newton iterations, or $\tilde{O}(n)$ FLOPS, where the tilde indicates that we neglect some polylogarithmic terms. This the first algorithm whose running time is proven optimal in the big-$\tilde{O}$ sense. Previous algorithms for the $p$-Laplacian required $\tilde{O}(\sqrt{n})$ damped Newton iterations or more.

math.NA↗
arXiv2020

Efficient algorithms for solving the $p$-Laplacian in polynomial time

The $p$-Laplacian is a nonlinear partial differential equation, parametrized by $p \in [1,\infty]$. We provide new numerical algorithms, based on the barrier method, for solving the $p$-Laplacian numerically in $O(\sqrt{n}\log n)$ Newton iterations for all $p \in [1,\infty]$, where $n$ is the number of grid points. We confirm our estimates with numerical experiments.

math.NA↗