Riemann-Oracle: A general-purpose Riemannian optimizer to solve nearness problems in matrix theory

Fuente: arXiv
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Autori principali: Gnazzo, Miryam, Noferini, Vanni, Nyman, Lauri, Poloni, Federico
Natura: Preprint
Pubblicazione: 2024
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author Gnazzo, Miryam
Noferini, Vanni
Nyman, Lauri
Poloni, Federico
author_facet Gnazzo, Miryam
Noferini, Vanni
Nyman, Lauri
Poloni, Federico
contents We propose an extremely versatile approach to address a large family of matrix nearness problems, possibly with additional linear constraints. Our method is based on splitting a matrix nearness problem into two nested optimization problems, of which the inner one can be solved either exactly or cheaply, while the outer one can be recast as an unconstrained optimization task over a smooth real Riemannian manifold. We observe that this paradigm applies to many matrix nearness problems of practical interest appearing in the literature, thus revealing that they are equivalent in this sense to a Riemannian optimization problem. We also show that the objective function to be minimized on the Riemannian manifold can be discontinuous, thus requiring regularization techniques, and we give conditions for this to happen. Finally, we demonstrate the practical applicability of our method by implementing it for a number of matrix nearness problems that are relevant for applications and are currently considered very demanding in practice. Extensive numerical experiments demonstrate that our method often greatly outperforms its predecessors, including algorithms specifically designed for those particular problems.
format Preprint
id arxiv_https___arxiv_org_abs_2407_03957
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Riemann-Oracle: A general-purpose Riemannian optimizer to solve nearness problems in matrix theory
Gnazzo, Miryam
Noferini, Vanni
Nyman, Lauri
Poloni, Federico
Numerical Analysis
65K10, 65F15, 65F22, 15A18, 15A22, 15A99, 49M37
We propose an extremely versatile approach to address a large family of matrix nearness problems, possibly with additional linear constraints. Our method is based on splitting a matrix nearness problem into two nested optimization problems, of which the inner one can be solved either exactly or cheaply, while the outer one can be recast as an unconstrained optimization task over a smooth real Riemannian manifold. We observe that this paradigm applies to many matrix nearness problems of practical interest appearing in the literature, thus revealing that they are equivalent in this sense to a Riemannian optimization problem. We also show that the objective function to be minimized on the Riemannian manifold can be discontinuous, thus requiring regularization techniques, and we give conditions for this to happen. Finally, we demonstrate the practical applicability of our method by implementing it for a number of matrix nearness problems that are relevant for applications and are currently considered very demanding in practice. Extensive numerical experiments demonstrate that our method often greatly outperforms its predecessors, including algorithms specifically designed for those particular problems.
title Riemann-Oracle: A general-purpose Riemannian optimizer to solve nearness problems in matrix theory
topic Numerical Analysis
65K10, 65F15, 65F22, 15A18, 15A22, 15A99, 49M37
url https://arxiv.org/abs/2407.03957