fcn = dft(20,'sin(2*x)');
plot(abs(fcn))
fv = idft(20,fcn);
plot(real(fv))

fcn = dft(20,'exp(-x).*sin(2*x)');
fv = idft(20,fcn);
plot(real(fv))


% Filtering
fcn = dft(200, 'sin(2*x) + sin(5*x) + 0.2*cos(50*x)');
plot(abs(fcn))
fv = idft(200,fcn);
plot(real(fv))

fcn_f = fcn.*window(200, 1,50);
fvn = idft(200,fcn_f);
figure(2); plot(real(fvn))

fcn_f2 = fcn_f.*window(200, 0,3);
fvn = idft(200,fcn_f2);
figure(3); plot(real(fvn))

fcn_f2 = fcn_f.*window(200, 4,7);
fvn = idft(200,fcn_f2);
figure(4); plot(real(fvn))