Prove eigenvalues are real

1. Jul 14, 2009

andrewm

Given a 4x4 non-Hermitian matrix, is there any method I can use to prove the eigenvalues are real, aside from actually computing them?

I'm looking for something like the converse of the statement "M is Hermitian implies M has real eigenvalues".

When can one say that the eigenvalues of a given matrix are real?

2. Jul 14, 2009

Pengwuino

In general, the eigenvalues of a non-Hermitian matrix can be complex. You would need to compute them.

3. Jul 15, 2009

andrewm

OK, I'm not surprised. Thanks anyways.