%MATLAB function s2z.m converts a network's generalized 
%scattering matrix, S, into the appertaining impedance
%matrix, Z.
%The function is called up by Z = s2z(Z0, S). It needs
%as its input arguments not only the elements of an
%S matrix, but also those of a normalizing reference
%impedance matrix, Z0.
%Z0 is a diagonal matrix whose elements are either
%real-valued (e.g., all diagonal elements
%are Z0 = 50 ohms) or complex-valued, i.e., with 
%a capacitive or inductive reactance term.

function[Z] = s2z(Z0, S)

D0= inv(sqrtm(Z0));
U = diag(ones(length(Z0),1));
Z = sqrtm(Z0)*inv(U-S)*(conj(Z0)+(S*Z0))*D0;