Author = Rezagholi, Sharifeh
Number of Articles: 1
On higher rank numerical hulls of normal matrices
Volume 4, Issue 1, 2017, Pages 23-32
https://doi.org/10.22072/wala.2017.47123.1080
Golamreza Aghamollaei, Sharifeh Rezagholi
Abstract In this paper, some algebraic and geometrical properties of the rank$-k$ numerical hulls of normal matrices are investigated. A characterization of normal matrices whose rank$-1$ numerical hulls are equal to their numerical range is given. Moreover, using the extreme points of the numerical range, the higher rank numerical hulls of matrices of the form $A_1 \oplus i A_2$, where $A_1$ and $A_2$ are Hermitian, are investigated. The higher rank numerical hulls of the basic circulant matrix are also studied.