fg_03_03.m

英文书《Digital Signal Processing with Examples in MATLAB》附带的MATLAB实例

% fg_03_03

% Chapter 3- discrete Fourier transform.
% Index vectors, n and m.
N=50;
n=[0:N-1];
m=[0:N-1];
% Sample vector, x.
x=[zeros(1,28),ones(1,12),zeros(1,N-40)];
% DFT, X.
X=x*exp(-j*2*pi*m'*n/N);
% Plots of x and |X|.
sp_fig(1); clf;
ha=axes('position',[.14,.22,.3,.5]);
set(gca,'fontname','times','fontsize',14);
line(n,x,'marker','o','color','k'); grid;
xlabel('n'); ylabel('x_n');
Title('Signal');
% 
axes('position',[.55,.22,.4,.5]);
set(gca,'fontname','times','fontsize',14);
line(n,abs(X),'marker','x','color','k'); grid;
xlabel('m'); ylabel('|X_m|');
Title('DFT magnitude');