Approximation of the numerical range of polynomial operator matrices
Μαρία Αδάμ, Aikaterini Aretaki, Ahmed Abdul-Muttalib Muhammad · Operators and Matrices · 2021
A linear operator on a Hilbert space may be approximated by finite matrices choosing an orthonormal basis of the Hilbert space. In this paper we establish an approximation of the q -numerical range of a bounded and an unbounded polynomial operator by variational methods. Applications to Hain-Lst operator and Stokes operator are also given.