1、3、实现步骤(1)单位抽样序列程序:x=zeros(1,10);x(2)=1;stem(x,filled)axis(0,10,-0.2,1);title();图1(2)单位阶跃序列N=10;u=ones(1,N); stem(u,axis(-10,10,0,1);图2(3)正弦序列x=-20:1:20;y=sin(0.2*pi.*x+0.5*pi);stem(x,y,axis(-20,20,-2,2);图3(4)实指数序列a=1/2n=0:10;a1=1/2;y1=a1.n;stem(n,y1,axis(0,10,0,1);a=1/2图45实指数序列a=2a2=2;y2=a2.n;stem(n
2、,y2,a=2图56 随机序列y=rand(1,20);stem(y,图6信号的移位:(1)信号移位n=-3:k0=3;k1=-3;%x=cos(2*pi*n/10);x1=cos(2*pi*(n-k0)/10);x2=cos(2*pi*(n-k1)/10);subplot(3,1,1),stem(n,x,ylabel(x(n)subplot(3,1,2),stem(n,x1,x(n-2)subplot(3,1,3),stem(n,x2,x(n+2)2信号相加、信号相乘x1=cos(2*pi*n/10);subplot(2,2,1);stem(n,x1,x(1)axis(-4,20,-2,2)
3、;x2=cos(2*pi*n/10);subplot(2,2,2);stem(n,x2,x(2)y=x1+x2;subplot(2,2,3);stem(n,y,y=x1.*x2;subplot(2,2,4);n=-5:5;x=exp(-0.4*n);x1=fliplr(x);n1=-fliplr(n);subplot(2,1,1),stem(n,x,subplot(2,1,2),stem(n1,x1,x(-n)信号和、信号积、信号能量:x=1,2,3,4,5,6,7,8,9;y1=sum(x)y2=prod(x)E1=sum(x.*conj(x)得到:y1 =45y2 =362880E1 =2
4、85 序列的波形;序列;(3) 描绘一下序列的波形function f=u(t)f=(t=0);subplot(2,1,1)n=-10:y1=(2*n+5).*(u(n+4)-u(n)+6.*(u(n)-u(n-5);axis(-10,10,-3,6);序列波形t=-10:subplot(2,1,2)y=(-3)*(u(t+4)-u(t+3)+(-1)*(u(t+3)-u(t+2)+(u(t+2)-u(t+1)+3*(u(t+1)-u(t)+6*(u(t)-u(t-1)+ 6*(u(t-1)-u(t-2)+6*(u(t-2)-u(t-3)+6*(u(t-3)-u(t-4)+6*(u(t-4)-u(t-5);stem(t,y,用单位脉冲序列及其加权和表示序列波形subplot(2,2,1)axis(-10,10,-6,12);subplot(2,2,2)stem(t+2,2*y,2x(n-2)subplot(2,2,3)stem(t-2,2*y,2x(n+2)subplot(2,2,4)stem(2-t,y,x(2-n)4、思考题当进行离散序列的相乘运算时,例1-6程序中有yp=xa1.*xa2,请问此处进行的相乘运算是矩阵乘还是数组乘,为何这样使用?答:此处进行的是数组乘,因为只有用数乘组,才能将序列中对应的数乘起来,实现序列相乘