Higham, Nicholas J. and Tisseur, Françoise
(2002)
*More on pseudospectra for polynomial eigenvalue problems and applications in control theory.*
Elsevier, Linear Algebra and its Applications, 351-35.
pp. 435-453.
ISSN 0024-3795

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## Abstract

Definitions and characterizations of pseudospectra are given for rectangular matrix poly-nomials expressed in homogeneous form: P(α,β)=α^dA_d+α^{d−1}βA_{d−1}+...+β^dA_0. It is shown that problems with infinite (pseudo)eigenvalues are elegantly treated in this framework. For such problems stereographic projection onto the Riemann sphere is shown to provide a convenient way to visualize pseudospectra. Lower bounds for the distance to the nearest nonregular polynomial and the nearest uncontrollable dth order system (with equality for standard state-space systems) are obtained in terms of pseudospectra, showing that pseudospectra are a fundamental tool for reasoning about matrix polynomials in areas such as control theory. How and why to incorporate linear structure into pseudospectra is also discussed by example.

Item Type: | Article |
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Uncontrolled Keywords: | Polynomial eigenvalue problem; λ-Matrix; Matrix polynomial; Homogeneous form; Pseudospectrum; Stereographic projection; Riemann sphere; Nearest nonregular polynomial; Nearest uncontrollable system; Structured perturbations |

Subjects: | MSC 2010, the AMS's Mathematics Subject Classification > 15 Linear and multilinear algebra; matrix theory MSC 2010, the AMS's Mathematics Subject Classification > 65 Numerical analysis |

Depositing User: | Ms Lucy van Russelt |

Date Deposited: | 27 Jun 2006 |

Last Modified: | 20 Oct 2017 14:12 |

URI: | https://eprints.maths.manchester.ac.uk/id/eprint/325 |

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