Linear Operators Preserving Generalized Numerical Ranges and Radii on Certain Triangular Algebras of Matrices
Wai-Shun Cheung, Chi-Kwong Li · Canadian Mathematical Bulletin · 2001
Abstract Let c = (c1, … , cn) be such that c1 ≥ … ≥ cn. The c-numerical range of an n × n matrix A is defined by and the c-numerical radius of A is defined by . We determine the structure of those linear operators ϕ on algebras of block triangular matrices, satisfying