Extraction of permeability and permmitivitty

Hi Folks,
I am trying to make a simple cubic slab 2.5mm length, and width (attached ?Slab_pict?). I have used normal solid materials and given eps =5 and mue=3 in CST. I would like to see the same obtaining parameter (eps and mue) when I extracted data of S11 and S21 data with frequency (0-12 GHz) in matlab code.

I have attached the Matlab code ?Nicholson.m? using single S11 and S21 parameter for testing which does run now. But, I do not know how to get epsilon and mue using range of S11 and S21 extracted data (attached data ?extraction_parameter?).

Hope you would help me in this issues.

Regards,
prince