1.Conv_m.m:function[y,ny]=conv_m(x,nx,h,nh)nyb=nx(1)+nh(1);nye=nx(length(x))+nh(length(h));ny=[nyb:nye];y=conv(x,h);2.impseq.m:function[x,n]=impseq(n0,n1,n2)n=[n1:n2]; x=[(n-n0)==0];3.stepseq.m:function[x,n]=stepseq(n0,n1,n2)n=[n1:n2];x=[(n-n0)>=0];2.38(1):n=[-4:3];x=2*impseq(-3,-4,3)-impseq(-2,-4,3)+2*impseq(0,-4,3) +4*impseq(-1,-4,3);subplot(2,2,1);stem(n,x);xlabel('n');ylabel('x(n)');2.38(2)n=[0:12];x=(0.8).^n.*(stepseq(0,0,12)-stepseq(10,0,12));stem(n,x);xlabel('n');ylabel('x(n)');n=[0:200];x=5*cos(0.04*pi*n)+0.3*randn(size(n));subplot(2,1,1);plot(n,x);xlabel('n');ylabel('x(n)');subplot(2,1,2);plot(n,x);xlabel('n');ylabel('x(n)');2.38(4)n=[-10:0.5:10];blta=-0.08+0.3j;x=exp(blta*n);subplot(2,2,1);stem(n,real(x));title('实部');xlabel('n');subplot(2,2,2);stem(n,imag(x));title('虚部');xlabel('n'); subplot(2,2,3);stem(n,abs(x));title('幅度');xlabel('n');subplot(2,2,4);stem(n,(180/pi)*angle(x));title('相位');xlabel('n');2.40x=[1,2,3,4,5];nx=[0:4];h=[1,-2,1,3];nh=[0:3];[y,ny]=conv_m(x,nx,h,nh)n=length(ny);x1=zeros(1,n);h1=zeros(1,n);x1(find((ny>=min(nx))&(ny<=max(nx))==1))=x;h1(find((ny>=min(nh))&(ny<=max(nh))==1))=h;subplot(3,1,1);stem(ny,x1);xlabel('n');ylabel('x(n)');subplot(3,1,2);stem(ny,h1);xlabel('n');ylabel('h(n)');subplot(3,1,3);stem(ny,y);xlabel('n');ylabel('h(n)');b=[1];a=[1,-1,0.9];x=impseq(0,-20,100);n=[-20:100];h=filter(b,a,x);subplot(2,1,1);stem(n,h);title('冲激响应');xlabel('n');ylabel('h(n)');x=stepseq(0,-20,100);s=filter(b,a,x);subplot(2,1,2);stem(n,s);title('阶跃响应');xlabel('n');ylabel('s(n)');z=roots(a);magz=abs(z)2.45(3)n=0:7;k=0:500;w=(pi/500)*k;X=(exp(-j*0.3*pi/500)).^(n'*k);magX=abs(X);angX=angle(X);subplot(2,1,1);plot(w/pi,magX);title('幅度响应');grid; ylabel('幅度');xlabel('以\pi为单位的频率');subplot(2,1,2);plot(w/pi,angX);title('相位响应');grid; ylabel('相位/\pi');xlabel('以\pi为单位的频率');2.47(3)b=[1,-1,0.5];a=[1,0.25,0.125];[R,P,C]=residuez(b,a);disp('R=');disp(R');disp('P=');disp(P');disp('C=');disp(C');:第三章function[Xk]=dft(xn,N)n=[0:1:N-1];k=[0:1:N-1];WN=exp(-j*2*pi/N);nk=n'*k;WNnk=WN.^nk;Xk=xn*WNnk;Idft.m:function[xn]=idft(Xk,N)n=[0:1:N-1];k=[0:1:N-1];WN=exp(-j*2*pi/N);nk=n'*k;WNnk=WN.^(-nk);xn=(Xk * WNnk)/N;3.22(1)x=[1,1,1,1];n=0:3;k=-200:200;w=(pi/100)*k;X=x*(exp(-j*pi/100)).^(n'*k);magX=abs(X);angX=angle(X)*180/pi;figure(1)subplot(2,1,1);plot(w/pi,magX);% axis([xmin xmax ymin ymax])axis([-1 1 0 4]);grid;title('DTFT的幅度');xlabel('以\pi为单位的频率');ylabel('幅度'); subplot(2,1,2);plot(w/pi,angX);grid;axis([-1 1 -200 200]);title('DTFT的相位');xlabel('以\pi为单位的频率');ylabel('相位');N=4;X=dft(x,N);magX=abs(X);phaX=angle(X)*180/pik=0:3;figure(2)subplot(2,1,1);stem(k,magX);title('DFT的幅度');xlabel('k');subplot(2,1,2);stem(k,phaX);title('DFT的相位');xlabel('k');x=[1,1,1,1,0,0,0,0];n=0:7;k=-200:200;w=(pi/100)*k;X=x*(exp(-j*pi/100)).^(n'*k);magX=abs(X);angX=angle(X)*180/pi; subplot(2,1,1);stem(k,magX);title('DFT的幅度');xlabel('k'); subplot(2,1,2);stem(k,phaX);title('DFT的相位');xlabel('k');3.23x=[1,1,1,1,0,0,0,0];n=0:7;k=-200:200;w=(pi/100)*k;X=x*(exp(-j*pi/100)).^(n'*k);magX=abs(X);angX=angle(X)*180/pi; figure(1)subplot(2,1,1);plot(w/pi,magX);N=8;X=dft(x,N);magX=abs(X);phaX=angle(X)*180/pi k=0:7;subplot(2,1,1);stem(k,magX);title('DFT的幅度');xlabel('k'); subplot(2,1,2);stem(k,phaX);title('DFT的相位');xlabel('k');3.29x=[1,1,1,1,0,0,0,0];n=0:7;k=-200:200;w=(pi/100)*k;X=x*(exp(-j*pi/100)).^(n'*k);magX=abs(X);angX=angle(X)*180/pi; figure(1)subplot(2,1,1);plot(w/pi,magX);N=8;X=dft(x,N);magX=abs(X);phaX=angle(X)*180/pi k=0:7;subplot(2,1,1);stem(k,magX); title('DFT的幅度');xlabel('k'); subplot(2,1,2);stem(k,phaX); title('DFT的相位');xlabel('k');。