Hi, I have a problem with the calculation of the eigenvalue of a matrix. That matrix is an N x N matrix which can be written as:(adsbygoogle = window.adsbygoogle || []).push({});

##M^{ab} = A\delta^{ab} + B \phi^a \phi^b##

where ##\delta^{ab}## is the identity matrix and the ##\phi## is a column vector. The paper I'm studying says that the eigenvalue of this matrix are:

A with molteplicity 1

##A + \phi^2 B## with molteplicity N-1

but I can't understand why! Can anyone help me?

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Eigenvalue and and eigenvector

**Physics Forums | Science Articles, Homework Help, Discussion**