Taylor's Theorem for Matrix Functions with Applications to Condition Number Estimation

Deadman, Edvin and Relton, Samuel (2016) Taylor's Theorem for Matrix Functions with Applications to Condition Number Estimation. Linear Algebra and its Applications, 504 (2015.2). pp. 354-371. ISSN 0024-3795

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Abstract

We derive an explicit formula for the remainder term of a Taylor polynomial of a matrix function. This formula generalizes a known result for the remainder of the Taylor polynomial for an analytic function of a complex scalar. We investigate some consequences of this result, which culminate in new upper bounds for the level-1 and level-2 condition numbers of a matrix function in terms of the pseudospectrum of the matrix. Numerical experiments show that, although the bounds can be pessimistic, they can be computed much faster than the standard methods. This makes the upper bounds ideal for a quick estimation of the condition number whilst a more accurate (and expensive) method can be used if further accuracy is required. They are also easily applicable to more complicated matrix functions for which no specialized condition number estimators are currently available.

Item Type: Article
Uncontrolled Keywords: matrix functions, Taylor series, remainder, condition number, pseudospectrum, Frechet derivative, Kronecker form
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: Dr Samuel Relton
Date Deposited: 31 May 2016
Last Modified: 20 Oct 2017 14:13
URI: https://eprints.maths.manchester.ac.uk/id/eprint/2479

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