demo3.m

这是一个 York大学开发的FDTD代码。很好用的工具

% uses setup from demo0
disp('Decaying Exponential (1st order) and its Spectrum')


disp('Generate time and frequency steps')
Ts=Tp/(N)
fs=1/Ts
f=linspace(0,fs*(N-1)/N,N);
disp('Generate time steps for one period (t)');
t=linspace(0,Tp*(N-1)/N,N);



disp('Generate time sequence (x) and plot it against time (t)')
x=1/Tor(1)*exp(-t/Tor(1));
title('Decaying exponential')
xlabel('Time')
plot(t,x);
input('Any key to continue')

disp('Generate DFT (X) of time series (x) and Compare with Fourier transform of continous data');
XD=Ts*fft(x);
XC=1./(1.+2*pi*f*Tor(1));
title( 'Fourier Transform (line) and Discrete Fourier Transform (o) Spectra')
xlabel('Frequency/fs')
ylabel( 'dB')
plot(f./fs,20*log10(abs(XD)),'o',f/fs,20*log10(abs(XC)),'-')