On certain finite dimensional numerical ranges and numerical radii
Moshe Goldberg · Linear and Multilinear Algebra · 1979
Abstract : This expository solicited paper consists of two parts: The first discusses properties of the classical numerical range and the corresponding numerical radius; the second is devoted to C-ranges and C-radii which are generalizations of the classical concepts. Although the ranges and radii treated here are associated with finite dimensional complex matrices, many of the mentioned results hold for linear operators on arbitrary Hilbert spaces as well. (Author)