Best approximation of a nonnormal operator in the trace norm
The author derives conditions under which a nonnormal operator has a unique positive approximant in trace norm. The author utilizes a result of \textit{T. Ando} [Linear Algebra Appl. 71, 15-21 (1985; Zbl 0577.41016)].
conditions under which a nonnormal operator has a unique positive approximant in trace norm
scientific article; zbMATH DE number 4075886