n = 500;
t = linspace(0, 10*pi, n);
x = sin(2*pi*t);
y = sin(2*pi*t + pi/2);

ex=sum(abs(x).^2);    
ey=sum(abs(y).^2);
fprintf("Time domain:\nex=%.1f, ey=%.1f\n", ex, ey)
ex=sum(abs(fft(x)).^2)/n;
ey=sum(abs(fft(y)).^2)/n;  
fprintf("Frequency domain (rectwin):\nex=%.1f, ey=%.1f\n", ex, ey)
w = hamming(n)';
ex=sum(abs(fft(x.*w)).^2)/sum(w.^2);
ey=sum(abs(fft(y.*w)).^2)/sum(w.^2);
fprintf("Frequency domain (hamming):\nex=%.1f, ey=%.1f\n", ex, ey)