h=[-4 1 -1 -2 5 6 5 -2 -1 1 -4];
n=0:length(h)-1;
[hr,w,a,L]=hr_type1(h);
amax=max(a)+1;
amin=min(a)-1;
subplot(2,2,1),stem(n,h),title('impulse response');grid on;
subplot(2,2,2),stem(0:L,a),title('a(n) coefficients');grid on;
subplot(2,2,3),plot(w/pi,hr),title('frequncy in pi units');grid on;
subplot(2,2,4),zplane(h,1),title('Type 1 amplitude response');grid on;