Involutions and angles between subspaces
Functional Analysis
2026-02-24 v1
Abstract
We provide a complete structure theorem for involutory matrices. This yields a new approach to principal angles between subspaces and provide a series of nice formulae for these angles.
Cite
@article{arxiv.2602.19599,
title = {Involutions and angles between subspaces},
author = {Jean-Christophe Bourin and Eun-Young Lee},
journal= {arXiv preprint arXiv:2602.19599},
year = {2026}
}
Comments
Some questions (at the end of the paper) on dilation into involutions have been completly answered in a recently published note by the author. (Dilating contractions into involutions and contraction, Linear Algebra Appl. 2026)