ex0311b.m

数字信号处理（机械工业出版社）的源码

% Discrete-time Signal
Ts = 0.001; n = -5:1:5;
x = exp(-1000*abs(n*Ts));
% Discrete-time Fourier transform
K = 500; k = 0:1:K;
w = pi*k/K;
X = x * exp(-j*n'*w);
X = real(X);
w = [-fliplr(w), w(2:K+1)];
X = [fliplr(X), X(2:K+1)];
subplot(2,1,1);
stem(n*Ts*1000,x); gtext('Ts=1 msec');
xlabel('t in msec.'); ylabel('x1(n)')
title('Discrete Signal');
subplot(2,1,2);plot(w/pi,X);
xlabel('Frequency in pi units'); ylabel('X1(w)')
title('Discrete-time Fourier Transform')