{"title":"On the Sensitivity of the Canonical Angles of a Unitoid Matrix","authors":"Kh. D. Ikramov, A. M. Nazari","doi":"10.1134/s199542392204005x","DOIUrl":null,"url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>A unitoid matrix is a square complex matrix that can be brought to diagonal form by a Hermitian congruence transformation. The canonical angles of a nonsingular unitoid matrix <span>\\(A\\)</span> are (up to the factor 1/2) the arguments of the eigenvalues of the cosquare of <span>\\(A\\)</span>, which is the matrix <span>\\(A^{-*}A\\)</span>. We derive an estimate for the derivative of an eigenvalue of the cosquare in the direction of the perturbation in <span>\\(A^{-*}A\\)</span> caused by a perturbation in <span>\\(A\\)</span>.</p>","PeriodicalId":43697,"journal":{"name":"Numerical Analysis and Applications","volume":"83 1","pages":""},"PeriodicalIF":0.4000,"publicationDate":"2022-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Numerical Analysis and Applications","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1134/s199542392204005x","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"MATHEMATICS, APPLIED","Score":null,"Total":0}
引用次数: 0
Abstract
A unitoid matrix is a square complex matrix that can be brought to diagonal form by a Hermitian congruence transformation. The canonical angles of a nonsingular unitoid matrix \(A\) are (up to the factor 1/2) the arguments of the eigenvalues of the cosquare of \(A\), which is the matrix \(A^{-*}A\). We derive an estimate for the derivative of an eigenvalue of the cosquare in the direction of the perturbation in \(A^{-*}A\) caused by a perturbation in \(A\).
期刊介绍:
Numerical Analysis and Applications is the translation of Russian periodical Sibirskii Zhurnal Vychislitel’noi Matematiki (Siberian Journal of Numerical Mathematics) published by the Siberian Branch of the Russian Academy of Sciences Publishing House since 1998.
The aim of this journal is to demonstrate, in concentrated form, to the Russian and International Mathematical Community the latest and most important investigations of Siberian numerical mathematicians in various scientific and engineering fields.
The journal deals with the following topics: Theory and practice of computational methods, mathematical physics, and other applied fields; Mathematical models of elasticity theory, hydrodynamics, gas dynamics, and geophysics; Parallelizing of algorithms; Models and methods of bioinformatics.