Nonconcavity of the Spectral Radius in Levinger's Theorem

Lee Altenberg, Joel E. Cohen

Let $\mathbf{A}\in R^{n\times n}$ be a nonnegative irreducible square matrix and let $r(\mathbf{A})$ be its spectral radius and Perron-Frobenius eigenvalue. Levinger asserted and sever…