Symmetric Nonnegative 5x5 Matrices Realizing Previously Unknown Region
  In this paper we present some symmetric nonnegative 5x5 matrix families that realize a previously unknown region. We also prove that these and other symmetric nonnegative 5x5 matrix families are closed under perturbations first presented in W. Guo. Eigenvalues of nonnegative matrices. Linear Algebra and its Applications, 266:261-270, 1997. 
Oren Spector
math.RA math.SP