fftexample.m

Signal and Sytem Using Matlab 书的源代码 注释详尽 m文件

%fft的应用举例
N=input('input N:');
T=input('input T:');
%compute the approximation of X(w)
t=0:T:2;
x=[t-1 zeros(1,N-length(t))];
Xk=fft(x);
gam=2*pi/N/T;
k=0:10/gam; %for plotting  pruposes
Xapp=(1-exp(-j*k*gam*T))/j/k/gam*Xk;
%compute the actual X(w)
w=0.05:0.05:10;
Xact=j*2*exp(-j*w).*(w.*cos(w)-sin(w))./(w.*w);
plot(k*gam,abs(Xapp(1:length(k))),'o',w,abs(Xact));