Remind that the Frobenius norm of the matrix \(A\) with the items \(A_{\mu\nu}\) is \((\sum_\mu \sum_nu|A_{\mu\nu}|^2)^{1/2}\). From the authors' abstract: ``using the notion of dual norms we show that, up to a scalar multiple, the maximum singular value is the only unitarily invariant induced norm. As a special case of this result, it follows that the Frobenius matrix norm is not induced.'' The contribution is motivated by the performance analysis of a control for its ability to reject disturbances.