demo9.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 Sinewave 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)')
wn=2*pi*f0(3); z=zeta(4);
%wn=2*pi*f0; z=zeta;
%kzm=(z-sqrt(z^2-1))*wn, kzp=(z+sqrt(z^2-1))*wn;
%x=wn/(sqrt(z^2-1))*(exp(-kzm*t) - exp(-kzp*t));
x=dampsin(t,wn,z);
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);
w=2*pi*f;
XC=dampsinf(w,wn,z);
title('Fourier Transform (x) and Discrete Fourier Transform Spectra (-)')
xlabel('Frequency/fs')
ylabel('dB')
plot(f/fs,20*log10(abs(XD)),'-',f/fs,20*log10(abs(XC)),'x');