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Mathematics of Computation

Published by the American Mathematical Society since 1960 (published as Mathematical Tables and other Aids to Computation 1943-1959), Mathematics of Computation is devoted to research articles of the highest quality in computational mathematics.

ISSN 1088-6842 (online) ISSN 0025-5718 (print)

The 2020 MCQ for Mathematics of Computation is 1.78.

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Computing the spectral gap of a family of matrices
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by Nicola Guglielmi and Vladimir Yu. Protasov
Math. Comp. 93 (2024), 259-291
DOI: https://doi.org/10.1090/mcom/3856
Published electronically: June 7, 2023

Abstract:

For a single matrix (operator) it is well-known that the spectral gap is an important quantity, as well as its estimate and computation. Here we consider, for the first time in the literature, the computation of its extension to a finite family of matrices, in other words the difference between the joint spectral radius (in short JSR, which we call here the first Lyapunov exponent) and the second Lyapunov exponent (denoted as SLE). The knowledge of joint spectral characteristics and of the spectral gap of a family of matrices is important in several applications, as in the analysis of the regularity of wavelets, multiplicative matrix semigroups and the convergence speed in consensus algorithms. As far as we know the methods we propose are the first able to compute this quantity to any given accuracy.

For computation of the spectral gap one needs first to compute the JSR. A popular tool that is used to this purpose is the invariant polytope algorithm, which relies on the finiteness property of the family of matrices, when this holds true.

In this paper we show that the SLE may not possess the finiteness property, although it can be efficiently approximated with an arbitrary precision. The corresponding algorithm and two effective estimates are presented. Moreover, we prove that the SLE possesses a weak finiteness property, whenever the leading eigenvalue of the dominant product is real. This allows us to find in certain situations the precise value of the SLE. Numerical results are demonstrated along with applications in the theory of multiplicative matrix semigroups and in the wavelets theory.

References
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Bibliographic Information
  • Nicola Guglielmi
  • Affiliation: Gran Sasso Science Institute (GSSI), via Crispi 7, I-67010 L’ Aquila, Italy
  • MR Author ID: 603494
  • Email: nicola.guglielmi@gssi.it
  • Vladimir Yu. Protasov
  • Affiliation: DISIM, University of L’Aquila, via Vetoio 1, I-67010 L’Aquila, Italy
  • MR Author ID: 607472
  • ORCID: 0000-0003-1862-2046
  • Email: vladimir.protasov@univaq.it
  • Received by editor(s): May 9, 2022
  • Received by editor(s) in revised form: March 13, 2023, and March 26, 2023
  • Published electronically: June 7, 2023
  • Additional Notes: The first author was supported by funds from the Italian MUR (Ministero dell’Università e della RicerSca) within the PRIN 2017 Project “Discontinuous dynamical systems: theory, numerics and applications”. The first author was also supported by the INdAM Research group GNCS (Gruppo Nazionale di Calcolo Scientifico). The second author was supported by the RFBR grant 20-01-00469.
    This article is dedicated to Sara
  • © Copyright 2023 American Mathematical Society
  • Journal: Math. Comp. 93 (2024), 259-291
  • MSC (2020): Primary 15A60, 15A42; Secondary 93D20, 47D03
  • DOI: https://doi.org/10.1090/mcom/3856