1,单位取样信号k=-5:5;delta=[zeros(1,5),1,zeros(1,5)];stem(k,delta)单位阶跃序列k=-5:5;delta=[zeros(1,5),ones(1,6)];stem(k,delta)正弦序列n=[0:0.1:20];x=11*sin(0.3*pi*n+pi/5)+5*cos(0.3*pi*n);plot(n,x)复正弦序列n=[0:19];w=pi/3;x=exp(j*w*n);stem(n,x)指数序列n=[0:50];x=(0.9).^n;stem(n,x)差分方程y[n]+0.75y[n−1]+0.125y[n−2]=x[n]−x[n−1]h(n)a1=[1,0.75,0.125];b1=[1,-1];n=0:20;x1=[1zeros(1,20)];y1filter=filter(b1,a1,x1);stem(n,y1filter);title('y1filter');xlabel('x');ylabel('y');阶跃响应a1=[1,0.75,0.125];b1=[1,-1];n=0:20;x2=ones(1,21);y1filter=filter(b1,a1,x2);stem(n,y1filter);title('y1filter_step');xlabel('x');ylabel('y')y[n]=0.25{x[n−1]+x[n−2]+x[n−3]+x[n−4]}a1=[1,];b1=[0.25,0.25,0.25,0.25];n=0:20;x1=[1zeros(1,20)];y1filter=filter(b1,a1,x1);stem(n,y1filter);title('y1filter');xlabel('x');ylabel('y');a1=[1];b1=[0.25,0.25,0.25,0.25];x2=ones(1,21);[h]=impz(b1,a1,20);y1=conv(h,x2);y1conv=y1(1:21);n1=0:20;stem(n1,y1conv,'filled');title('y1conv');xlabel('n');ylabel('y1[n]');求H（Z）零极点和频率响应b=[0.0528,0.0797,0.1295,0.1295,0,797,0,0528];a=[1,-1.8107,2.4947,-1.8801,0.9537,-0.2336];zplane(b,a);title('零极点');[H,w]=freqz(b,a,'whole');magH=abs(H(1:101));phaH=angle(H(1:101));w=w(1:101);figure(2);subplot(2,1,1);plot(w/pi,magH);gridxlabel('frequencyUnit：pi);ylabel('Magnitude');title('magnituderesponse');...subplot(2,1,2);plot(w/pi,phaH/pi);gridxlabel('frequencyUnit:pi');ylabel('PhaseUnit:pi');title('PhaseResponse');