function [real_z_index,comp_z_index] = class_real_comp(z)
% the function to classify the real zero/poles and complex zero/poles
% the complex zero/poles list has only one pole/zero of pole/zero conjugate
% pares.
comp_z_index = [];
real_z_index = [];
comp_z = [];
for ii = 1:length(z)
    if isreal(z(ii))
        real_z_index = [real_z_index ii];
    else
        if not(sum(mnismember(comp_z,conj(z(ii)))))
            comp_z = [comp_z z(ii)];
            comp_z_index = [comp_z_index ii];
        end
    end
end