function bodehzhz(h, w)
% same as bodehz, but draws only phase response

r = freqresp(h, w);
lines = findobj(findobj(gcf, 'Type', 'axes'), 'Type', 'line');
color = [ 'b'; 'g'; 'r'; 'c'; 'm'; 'y'; 'k' ];
i = mod(length(lines), length(color)) + 1;

if islinspace(w)
    plot(w/2/pi, 180/pi * unwrap(angle(r(1, :))), color(i));
else
    semilogx(w/2/pi, 180/pi * unwrap(angle(r(1, :))), color(i));
end
xlabel('Frequency [Hz]');
ylabel('Phase [degrees]');
