Geometric of numerical and quadratic numerical range for block operator matrices
Amer M. Salman, Ahmad Izani Md. Ismail, Maisarah Haji Mohd, Ahmed Abdul-Muttalib Muhammad · AIP conference proceedings · 2021
In this paper, some established properties and results on numerical range and quadratic numerical range of block operator matrices are studied and compared. These results and properties are then applied to compute both ranges for block operator matrices of self-adjoint as well as non-self-adjoint types in the complex Hilbert space.