% Chapter 7: Example 7.4 Type-1 Linear phase FIR filter%subplot(1,1,1)h = [-4,1,-1,-2,5,6,5,-2,-1,1,-4];M = length(h); n = 0:M-1;[Hr,w,a,L] = Hr_Type1(h);amax = max(a)+1; amin = min(a)-1;subplot(2,2,1); stem(n,h); axis([-1 2*L+1 amin amax])xlabel('n'); ylabel('h(n)'); title('Impulse Response')subplot(2,2,3); stem(0:L,a); axis([-1 2*L+1 amin amax])xlabel('n'); ylabel('a(n)'); title('a(n) coefficients')subplot(2,2,2);plot(w/pi,Hr);gridxlabel('frequency in pi units'); ylabel('Hr')title('Type-1 Amplitude Response')subplot(2,2,4);pzplotz(h,1)