% Compute the mixed transfer function tf at a frequency f.
% tf is a struct array with fields Hs and Hz wich represent
% a continuous-time/discrete-time tfs which must be multiplied together
% and then added up.
df = 1e-5;
H = zeros(size(f));
for i = 1:length(tf)
H = H + evalTFP(tf(i).Hs,tf(i).Hz,f);
err = find(isnan(H)|isinf(H));
% Need to fill in the holes. !! Use a "nearby" frequency point
H(i) = evalMixedTF(tf,f(i)+df,df*10);