Kippenhahn curves of some tridiagonal matrices
Natália Bebiano, João da Providência, Ilya M. Spitkovsky, Kenya Vazquez · Filomat · 2021
Tridiagonal matrices with constant main diagonal and reciprocal pairs of off-diagonal entries are considered. Conditions for such matrices with sizes up to 6-by-6 to have elliptical numerical ranges are obtained.