example3_13.m

西交大刘树棠写的《数字信号处理》那本书的所有源代码

N=5;k=0:1:N-1;
wk=2*pi*k/N;
zk=exp(j*wk);
Xk=zk./(zk-0.7);
xn=real(idfs(Xk,N));
xtilde=xn'*ones(1,8);
xtilde=(xtilde(:))';
subplot(2,2,1);stem(0:39,xtilde);axis([0,40,-0.1,1.5]);
xlabel('n');
ylabel('xtilde(n)');
title('N-5');

N=10;k=0:1:N-1;
wk=2*pi*k/N;
zk=exp(j*wk);
Xk=zk./(zk-0.7);
xn=real(idfs(Xk,N));
xtilde=xn'*ones(1,4);
xtilde=(xtilde(:))';
subplot(2,2,2);stem(0:39,xtilde);axis([0,40,-0.1,1.5]);
xlabel('n');
ylabel('xtilde(n)');
title('N-10');

N=20;k=0:1:N-1;
wk=2*pi*k/N;
zk=exp(j*wk);
Xk=zk./(zk-0.7);
xn=real(idfs(Xk,N));
xtilde=xn'*ones(1,2);
xtilde=(xtilde(:))';
subplot(2,2,3);stem(0:39,xtilde);axis([0,40,-0.1,1.5]);
xlabel('n');
ylabel('xtilde(n)');
title('N-20');

N=40;k=0:1:N-1;
wk=2*pi*k/N;
zk=exp(j*wk);
Xk=zk./(zk-0.7);
xn=real(idfs(Xk,N));
xtilde=xn'*ones(1,1);
xtilde=(xtilde(:))';
subplot(2,2,4);stem(0:39,xtilde);axis([0,40,-0.1,1.5]);
xlabel('n');
ylabel('xtilde(n)');
title('N-40');