Problem about calculating the eigenvalue using the output impedance matrix from FEKO

Hello, every, can you help me on the following question?

So many values of the output impedance matrix from feko is too small, i can't use the eig(X,R) function from matlab to calculate the eigenvalue,I don't konw how to deal with .R and X are the real and imag part of the impedance matrix;


Could you give me some help on this issue?
Thanks a lot!