% Chapter 7: Example 7.22%            Error function plot and counting of extremafigure(1);subplot(1,1,1)h = [1,2,3,4,3,2,1]/15;M = length(h); n = 0:M-1;[Hr,w,a,L] = Hr_Type1(h);subplot(1,2,1);plot(w/pi,Hr);axis([0,1,-0.05,1.1])xlabel('frequency in pi units');title('Amplitude Response');hold onwp = w(1:52); ws = w(197:500);upb=Hr(1)*ones(length(wp),1);lpb=(2-Hr(1))*ones(length(wp),1);ipb=ones(length(wp),1);plot(wp/pi,upb,'r',wp/pi,ipb,'g',wp/pi,lpb,'r')usb=Hr(197)*ones(length(ws),1);lsb=zeros(length(ws),1);isb=0.5*usb;plot(ws/pi,usb,'r',ws/pi,isb,'g',ws/pi,lsb,'r');set(gca,'XTickMode','manual','XTick',[0,0.1,0.39,1])set(gca,'XTickLabelMode','manual','XTickLabels',[' 0 ';'0.1';'0.4';' 1 '])set(gca,'XGrid','on')set(gca,'YTickMode','manual','YTick',[0,0.0394,0.0787,0.933,1,1.067])set(gca,'YTickLabelMode','manual',...        'YTickLabels',['-0.04';' 0.0 ';' 0.04';' 0.93';' 1.0 ';' 1.07'])hold off%%Error function plotssubplot(1,2,2); erpb=Hr(1:52)-ipb; ersb=Hr(197:500)-isb;plot(wp/pi,erpb,ws/pi,ersb); axis([0,1,-.55,.55]);xlabel('frequency in pi units');title('Error Function');hold onplot(wp/pi,upb-ipb,'r',wp/pi,lpb-ipb,'r')plot(ws/pi,usb-isb,'r',ws/pi,lsb-isb,'r');set(gca,'XTickMode','manual','XTick',[0,0.1,0.39,1])set(gca,'XTickLabelMode','manual','XTickLabels',[' 0 ';'0.1';'0.4';' 1 '])set(gca,'XGrid','on')set(gca,'YTickMode','manual','YTick',[-0.07,0,0.07])hold off