21 citations · 24 across the 5 of their papers we have counts for
4 papers · 1 filter
The numerical range of periodic banded Toeplitz operators
Benjamín A. Itzá-Ortiz, Rubén A. Martínez-Avendaño, Hiroshi Nakazato
We prove that the closure of the numerical range of a -periodic and -banded Toeplitz operator can be expressed as the closure of the convex hull of the uncountable u…
The numerical range of some periodic tridiagonal operators is the convex hull of the numerical ranges of two finite matrices
Benjamín A. Itzá-Ortiz, Rubén A. Martínez-Avendaño, Hiroshi Nakazato
In this paper we prove a conjecture stated by the first two authors establishing the closure of the numerical range of a certain class of -periodic tridiagonal operators as th…
The numerical range of a periodic tridiagonal operator reduces to the numerical range of a finite matrix
Benjamín A. Itzá-Ortiz, Rubén A. Martínez-Avendaño, Hiroshi Nakazato
In this paper we show that the closure of the numerical range of an -periodic tridiagonal operator is equal to the numerical range of a complex matrix.
Norm-parallelism and the Davis--Wielandt radius of Hilbert space operators
A. Zamani, M. S. Moslehian, M. T. Chien +1
We present a necessary and sufficient condition for the norm-parallelism of bounded linear operators on a Hilbert space. We also give a characterization of the Birkhoff--James orth…