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20242026
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math.NA2026

Multilevel Isogeometric Projection Stabilization via Quasi-Interpolation for Advection-Dominated Problems

Zakaria El Hasnaoui, Ahmed Ratnani

This paper presents a novel multilevel projection-based stabilization method for advection-dominated convection--diffusion problems within the framework of Isogeometric Analysis. T…

math.NA2026

Block Schwarz methods and preconditioning strategies using Generalized locally Toeplitz tools - part I: analysis of the preconditioners and numerical validation

Abdessadek Rifqui, Ahmed Ratnani, Stefano Serra-Capizzano

In the current work we present a spectral analysis of the additive and multiplicative Schwarz methods within the framework of domain decomposition techniques, by investigating the…

math.NA20251 cited

Higher order multi-dimension reduction methods via Einstein product

Alaeddine Zahir, Khalide Jbilou, Ahmed Ratnani

This paper explores the extension of dimension reduction (DR) techniques to the multi-dimension case by using the Einstein product. Our focus lies on graph-based methods, encompass…

math.NA2025

Trace Ratio vs Ratio Trace Methods for Multidimensional Dimensionality Reduction

Alaeddine Zahir, Franck Dufrenois, Khalide Jbilou +1

We propose a higher-order dimensionality reduction framework based on the Trace Ratio (TR) optimization problem. We establish conditions for existence and uniqueness of solutions a…

math.NA20251 cited

Quaternion tensor low rank Quaternion tensor low-rank approximation using a family of non-convex norms

Alaeddine Zahir, Ahmed Ratnani, Khalide Jbilou

In this paper, we propose a new approaches for low rank approximation of quaternion tensors \cite{chen2019low,zhang1997quaternions,hamilton1866elements}. The first method uses quas…

math.NA2025

IGA Laplace Eigenfrequencies Distributions and Estimations: Impact of Reparametrization on Eigenfrequency Behavior

Lamsahel Noureddine, Abdeladim El Akri, Ahmed Ratnani

This work addresses the Galerkin isogeometric discretization of the one-dimensional Laplace eigenvalue problem subject to homogeneous Dirichlet boundary conditions on a bounded int…