A note on Guo's perturbation result for symmetric nonnegative matrices

Helena Šmigoc

In 1997 Guo Wuwen proved that if $({\lambda }_1,{\lambda }_2,\dots ,{\lambda }_n)$ is the spectrum of a nonnegative matrix with Perron eigenvalue ${\lambda }_1$ and ${\lambda }_2$ real, then $({\lambda }_1+t,{\lambda }_2\pm t,{\lambda }_3,\dots ,{\lambda }_n)$ is…