Spectra and pseudospectra of the direct sum operators
1Karadeniz Technical University, Department of Mathematics, TRABZON
Sigma J Eng Nat Sci 2020; 38(3): 1251-1259
Abstract
In this paper, the relationships between spectrum and pseudospectrum of the direct sum of linear operators in the direct sum of Hilbert spaces and its coordinate operators have been researched. Also, the analogous relations of some numerical characteristics (spectral and pseudospectral radii) of such operators have been investigated.
Keywords: Direct sum of operators, spectrum, pseudospectrum, spectral radii.
