Beyond singular value gaps in randomized subspace approximation

Fuente: arXiv
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Auteurs principaux: Wang, Christopher, Townsend, Alex
Format: Preprint
Publié: 2026
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author Wang, Christopher
Townsend, Alex
author_facet Wang, Christopher
Townsend, Alex
contents The success of randomized range finders (RRFs) is typically analyzed via the singular value gaps of a target matrix $A$. In this work, we show that the so-called Frobenius singular value ratio provides a sharper analysis of an RRF's subspace quality under Gaussian sketching. For any matrix $A$ and any integer $k\ge0$, we derive an explicit, closed-form expression for the cumulative distribution function of the largest principal angle between the $k$-dominant singular subspace of $A$ and the approximate RRF subspace, expressing it in terms of a hypergeometric function. We obtain definitive probabilistic guarantees for RRFs that are strictly stronger than those obtained previously.
format Preprint
id arxiv_https___arxiv_org_abs_2603_01191
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Beyond singular value gaps in randomized subspace approximation
Wang, Christopher
Townsend, Alex
Numerical Analysis
65F55, 15A18, 68W20 (Primary) 60B20, 62H10, 62R30 (Secondary)
The success of randomized range finders (RRFs) is typically analyzed via the singular value gaps of a target matrix $A$. In this work, we show that the so-called Frobenius singular value ratio provides a sharper analysis of an RRF's subspace quality under Gaussian sketching. For any matrix $A$ and any integer $k\ge0$, we derive an explicit, closed-form expression for the cumulative distribution function of the largest principal angle between the $k$-dominant singular subspace of $A$ and the approximate RRF subspace, expressing it in terms of a hypergeometric function. We obtain definitive probabilistic guarantees for RRFs that are strictly stronger than those obtained previously.
title Beyond singular value gaps in randomized subspace approximation
topic Numerical Analysis
65F55, 15A18, 68W20 (Primary) 60B20, 62H10, 62R30 (Secondary)
url https://arxiv.org/abs/2603.01191