On some reciprocal matrices with elliptical components of their Kippenhahn curves

Muyan Jiang, Ilya M. Spitkovsky

Research output: Contribution to journalArticlepeer-review

Abstract

By definition, reciprocal matrices are tridiagonal n-by-n matrices A with constant main diagonal and such that ai,i+1ai+1,i= 1 for i = 1,..., n - 1. We establish some properties of the numerical range generating curves C(A) (also called Kippenhahn curves) of such matrices, in particular concerning the location of their elliptical components. For n ≤ 6, in particular, we describe completely the cases when C(A) consist entirely of ellipses. As a corollary, we also provide a complete description of higher rank numerical ranges when these criteria are met.

Original languageEnglish (US)
Pages (from-to)117-130
Number of pages14
JournalSpecial Matrices
Volume10
Issue number1
DOIs
StatePublished - Jan 1 2022

Keywords

  • Kippenhahn curve
  • Numerical range
  • Reciprocal matrix

ASJC Scopus subject areas

  • Algebra and Number Theory
  • Geometry and Topology

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