Extremal signatures for bivariate Chebyshev approximation problems (Q1315202)

The problem of finding a Chebyshev solution of the real matrix equation \(AX+ YB= C\), where \(C\) is an \(m\times n\) matrix, is considered. This equation corresponds to a linear system \([I_ n\otimes A,\;B^ T\otimes I_ m] Z= d\). The characterization and the computation of best linear Chebyshev approximations are connected with the notion of extremal signature. The purpose of this paper is to analyze the extremal signatures of this problem.