Limited approximation of numerical range of normal matrix

Adam, M; Maroulas, J

dc.contributor.author	Adam, M	en
dc.contributor.author	Maroulas, J	en
dc.date.accessioned	2014-03-01T01:33:42Z
dc.date.available	2014-03-01T01:33:42Z
dc.date.issued	2010	en
dc.identifier.issn	1846-3886	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/20543
dc.relation.uri	http://www.scopus.com/inward/record.url?eid=2-s2.0-77954919595&partnerID=40&md5=333ccd5756713fd3e7c48089458b210a	en
dc.subject	Compression	en
dc.subject	Eigenvalue	en
dc.subject	Numerical range	en
dc.subject.other	NORMAL COMPRESSION	en
dc.title	Limited approximation of numerical range of normal matrix	en
heal.type	journalArticle	en
heal.language	English	en
heal.publicationDate	2010	en
heal.abstract	Let A be an n x n normal matrix, whose numerical range NR[A] is a k-polygon. If a unit vector v is an element of W subset of C-n, with dimW = k and the point vAv is an element of IntNR[A], then NR[A] is circumscribed to NR[PAP], where P is an n x (k-1) isometry of {span{v}}(W)(perpendicular to) -> C-n, [1]. In this paper, we investigate an internal approximation of NR[ A] by an increasing sequence of NR[C-s] of compressed matrices C-s = R-sAR(s), with R-sR-s = Ik+s-1, s = 1,2,..., n - k and additionally NR[A] is expressed as limit of numerical ranges of k-compressions of A.	en
heal.publisher	ELEMENT	en
heal.journalName	Operators and Matrices	en
dc.identifier.isi	ISI:000273612500007	en
dc.identifier.volume	4	en
dc.identifier.issue	1	en
dc.identifier.spage	139	en
dc.identifier.epage	149	en