Plotting a continuous-time signal and its spectrum
2 X(f) = ------------ 2 1 + (2 pi f)The following MATLAB program will plot x(t) and X(f) (in dB).
tmax = 5; % 5 time constants t = -tmax:.001:tmax; x = exp(-abs(t)); subplot(211) plot(t,x) xlabel('t (sec)') ylabel('x(t)') title('x(t) = exp(-|t|)'); f = -5:.001:5; X = 2./(1+(2*pi*f).^2); subplot(212) plot(f,20*log10(abs(X))) xlabel('f (Hz)') ylabel('|X(f)| (dB)')