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Orbit closure hierarchies of skew-symmetric matrix pencils
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N).
2014 (Engelska)Ingår i: SIAM Journal on Matrix Analysis and Applications, ISSN 0895-4798, E-ISSN 1095-7162, Vol. 35, nr 4, s. 1429-1443Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

We study how small perturbations of a skew-symmetric matrix pencil may change its canonical form under congruence. This problem is also known as the stratification problem of skew-symmetric matrix pencil orbits and bundles. In other words, we investigate when the closure of the congruence orbit (or bundle) of a skew-symmetric matrix pencil contains the congruence orbit (or bundle) of another skew-symmetric matrix pencil. The developed theory relies on our main theorem stating that a skew-symmetric matrix pencil A - lambda B can be approximated by pencils strictly equivalent to a skew-symmetric matrix pencil C - lambda D if and only if A - lambda B can be approximated by pencils congruent to C - lambda D.

Ort, förlag, år, upplaga, sidor
2014. Vol. 35, nr 4, s. 1429-1443
Nyckelord [en]
skew-symmetric matrix pencil, stratification, canonical structure information, orbit, bundle
Nationell ämneskategori
Datavetenskap (datalogi)
Identifikatorer
URN: urn:nbn:se:umu:diva-98914DOI: 10.1137/140956841ISI: 000346843200010OAI: oai:DiVA.org:umu-98914DiVA, id: diva2:784021
Forskningsfinansiär
eSSENCE - An eScience CollaborationVetenskapsrådet, A0581501Tillgänglig från: 2015-01-28 Skapad: 2015-01-28 Senast uppdaterad: 2018-06-07Bibliografiskt granskad
Ingår i avhandling
1. Tools for Structured Matrix Computations: Stratifications and Coupled Sylvester Equations
Öppna denna publikation i ny flik eller fönster >>Tools for Structured Matrix Computations: Stratifications and Coupled Sylvester Equations
2015 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Developing theory, algorithms, and software tools for analyzing matrix pencils whose matrices have various structures are contemporary research problems. Such matrices are often coming from discretizations of systems of differential-algebraic equations. Therefore preserving the structures in the simulations as well as during the analyses of the mathematical models typically means respecting their physical meanings and may be crucial for the applications. This leads to a fast development of structure-preserving methods in numerical linear algebra along with a growing demand for new theories and tools for the analysis of structured matrix pencils, and in particular, an exploration of their behaviour under perturbations. In many cases, the dynamics and characteristics of the underlying physical system are defined by the canonical structure information, i.e. eigenvalues, their multiplicities and Jordan blocks, as well as left and right minimal indices of the associated matrix pencil. Computing canonical structure information is, nevertheless, an ill-posed problem in the sense that small perturbations in the matrices may drastically change the computed information. One approach to investigate such problems is to use the stratification theory for structured matrix pencils. The development of the theory includes constructing stratification (closure hierarchy) graphs of orbits (and bundles) that provide qualitative information for a deeper understanding of how the characteristics of underlying physical systems can change under small perturbations. In turn, for a given system the stratification graphs provide the possibility to identify more degenerate and more generic nearby systems that may lead to a better system design.

We develop the stratification theory for Fiedler linearizations of general matrix polynomials, skew-symmetric matrix pencils and matrix polynomial linearizations, and system pencils associated with generalized state-space systems. The novel contributions also include theory and software for computing codimensions, various versal deformations, properties of matrix pencils and matrix polynomials, and general solutions of matrix equations. In particular, the need of solving matrix equations motivated the investigation of the existence of a solution, advancing into a general result on consistency of systems of coupled Sylvester-type matrix equations and blockdiagonalizations of the associated matrices.

Ort, förlag, år, upplaga, sidor
Umeå: Umeå universitet, 2015. s. 29
Serie
Report / UMINF, ISSN 0348-0542 ; 15.18
Nationell ämneskategori
Data- och informationsvetenskap
Identifikatorer
urn:nbn:se:umu:diva-111641 (URN)978-91-7601-379-3 (ISBN)
Disputation
2015-12-11, MA 121 MIT-building, Umeå universitet, Umeå, 13:00 (Engelska)
Opponent
Handledare
Forskningsfinansiär
Vetenskapsrådet, E0485301Vetenskapsrådet, A0581501eSSENCE - An eScience Collaboration
Tillgänglig från: 2015-11-20 Skapad: 2015-11-18 Senast uppdaterad: 2018-06-07Bibliografiskt granskad

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Dmytryshyn, AndriiKågstrom, Bo

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