n=30;
f=[0 0.4 0.5 1];
a=[1 1 0 0];
b=firls(n,f,a);
[h,w]=freqz(b);
bb=remez(n,f,a);
[hh,w]=freqz(bb);
axes('position',[0.2 0.2 0.5 0.5]);
plot(w/pi,abs(h),'b-',w/pi,abs(hh),'r--');
xlabel('frequency(pi)');
ylabel('magnitude');
title('direct IIR design-yulewalk');
legend('firls','remez');
grid