Philis Alosa

Spectral Radius of a Normal Operator

Achiles Nyongesa Simiyu, Philis Alosa & Fanuel Olege · Asian Research Journal of Mathematics · 2022

Let X be a Complex Banach space and T be a bounded operator in X. The number sup {|λ| : λ ∈ σ(T)} (where σ(T) is the spectrum of T and σ(T) ̸= ϕ) is called the spectral radius of T and denoted by r(T). Since λ ≤ ∥T∥for all λ ∈ σ(T), it follows that r(T) ≤ ∥T∥. The spectral mappin...