Hiroshi Nakazato

activity

20182023

most citedNorm-parallelism and the Davis--Wielandt radius of Hilbert space operators

21 citations · 24 across the 5 of their papers we have counts for

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2 papers · 1 filter

math.FA2023

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 $(n + 1)$ -periodic and $(2 m + 1)$ -banded Toeplitz operator can be expressed as the closure of the convex hull of the uncountable u…

math.CO2023

Numerical ranges of cyclic shift matrices

Mao-Ting Chien, Steve Kirkland, Chi-Kwong Li +1

We study the numerical range of an $n \times n$ cyclic shift matrix, which can be viewed as the adjacency matrix of a directed cycle with $n$ weighted arcs. In particular, we consid…