M2-1(1)t=-2:0.001:4;T=2;xt=rectpuls(t-1,T);plot(t,xt)axis([-2,4,-0.5,1.5])图象为：(2)t=sym('t');y=Heaviside(t);ezplot(y,[-1,1]);gridonaxis([-11-0.11.1])图象为：(3)A=10;a=-1;B=5;b=-2;t=0:0.001:10;xt=A*exp(a*t)-B*exp(b*t);plot(t,xt)图象为：(4)t=sym('t');y=t*Heaviside(t);ezplot(y,[-1,3]);gridonaxis([-13-0.13.1])图象为：(5)A=2;w0=10*pi;phi=pi/6;t=0:0.001:0.5;xt=abs(A*sin(w0*t+phi));plot(t,xt)图象为：(6)A=1;w0=1;B=1;w1=2*pi;t=0:0.001:20;xt=A*cos(w0*t)+B*sin(w1*t);plot(t,xt)图象为：(7)A=4;a=-0.5;w0=2*pi;t=0:0.001:10;xt=A*exp(a*t).*cos(w0*t);plot(t,xt)图象为：(8)w0=30;t=-15:0.001:15;xt=cos(w0*t).*sinc(t/pi);plot(t,xt)axis([-15,15,-1.1,1.1])图象为：M2-3（1）functionyt=x2_3(t)yt=(t).*(t>=0&t<=2)+2*(t>=2&t<=3)-1*(t>=3&t<=5);（2）functionyt=x2_3(t)yt=(t).*(t>=0&t<=2)+2*(t>=2&t<=3)-1*(t>=3&t<=5);t=0:0.001:6;subplot(3,1,1)plot(t,x2_3(t))title('x(t)')axis([0,6,-2,3])subplot(3,1,2)plot(t,x2_3(0.5*t))title('x(0.5t)')axis([0,11,-2,3])subplot(3,1,3)plot(t,x2_3(2-0.5*t))title('x(2-0.5t)')axis([-6,5,-2,3])图像为：M2-9（1）k=-4:7;xk=[-3,-2,3,1,-2,-3,-4,2,-1,4,1,-1];stem(k,xk,'file')（2）k=-12:21;x=[-3,0,0,-2,0,0,3,0,0,1,0,0,-2,0,0,-3,0,0,-4,0,0,2,0,0,-1,0,0,4,0,0,1,0,0,-1];subplot(2,1,1)stem(k,x,'file')title('3倍内插')t=-1:2;y=[-2,-2,2,1];subplot(2,1,2)stem(t,y,'file')title('3倍抽取')axis([-3,4,-4,4])（3）k=-4:7;x=[-3,-2,3,1,-2,-3,-4,2,-1,4,1,-1];subplot(2,1,1)stem(k+2,x,'file')title('x[k+2]')subplot(2,1,2)stem(k-4,x,'file')title('x[k-4]')（4）k=-4:7;x=[-3,-2,3,1,-2,-3,-4,2,-1,4,1,-1];stem(-fliplr(k),fliplr(x),'file')title('x[-k]')M3-1（1）ts=0;te=5;dt=0.01;sys=tf([21],[132]);t=ts:dt:te;x=exp(-3*t);y=lsim(sys,x,t);plot(t,y)xlabel('Time(sec)')ylabel('y(t)')（2）ts=0;te=5;dt=1;sys=tf([21],[132]);t=ts:dt:te;x=exp(-3*t);y=lsim(sys,x,t)y=00.6649-0.0239-0.0630-0.0314-0.0127从（1）（2）对比我们当抽样间隔越小时数值精度越高。M3-4x=[0.85,0.53,0.21,0.67,0.84,0.12];kx=-2:3;h=[0.68,0.37,0.83,0.52,0.71];kh=-1:3;y=conv(x,h);k=kx(1)+kh(1):kx(end)+kh(end);stem(k,y,'file');M3-8k=0:30;a=[10.7-0.45-0.6];b=[0.8-0.440.360.02];h=impz(b,a,k);stem(k,h,'file')M4-1（1）对于周期矩形信号的傅里叶级数cn=-1/2j*sin(n/2*pi)*sinc(n/2)n=-15:15;X=-j*1/2*sin(n/2*pi).*sinc(n/2);subplot(2,1,1);stem(n,abs(X),'file');title('幅度谱')xlabel('nw');subplot(2,1,2);stem(n,angle(X),'file');title('相位谱')（2）对于三角波信号的频谱是：Cn=-++n=-15:15;X=sinc(n)-0.5*((sinc(n/2)).^2);subplot(2,1,1);stem(n,abs(X),'file');title('幅度谱')xlabel('nw');subplot(2,1,2);stem(n,angle(X),'file');title('相位谱')M4-6(4)x=[1,2,3,0,0];X=fft(x,5);subplot(2,1,1);m=0:4;stem(m,real(X),'file');title('X[m]实部')subplot(2,1,2);stem(m,imag(X),'file');title('X[m]虚部')M4-7（3）k=0:10;x=0.5.^k;subplot(3,1,1);stem(k,x,'file')title('x[k]')X=fft(x,10);subplot(3,1,2);m=0:9;stem(m,real(X),'file');title('X[m]实部')subplot(3,1,3);stem(m,imag(X),'file');title('X[m]虚部')M5-2t=0:0.05:2.5;T=1;xt1=rectpuls(t-0.5,T);subplot(2,2,1)plot(t,xt1)title('x(t1)')axis([0,2.5,0,2])xt2=tripuls(t-1,2);subplot(2,2,2)plot(t,xt2)title('x(t2)')axis([0,2.5,0,2])xt=xt1+xt2.*cos(50*t);subplot(2,2,[3,4])plot(t,xt)title('x(t)')figure;b=[10000];a=[1,26.131,341.42,2613.1,10000];w=linspace(0,2*pi,200);[H,w]=freqs(b,a,w);subplot(2,1,1)plot(w,abs(H));title('幅度曲线')subplot(2,1,2)plot(w,angle(H));title('相位曲线')figure;sys=tf([10000],[126.131341.422613.110000]);yt1=lsim(sys,xt,t);subplot(2,1,1);plot(t,y...
