Whiteness test

Whiteness test of a signal

This function gives several attributes of a signal to determine if it is approximately a white noise:

1. Figure with autocorrelation values
2. Spectrum (it has been approximately a flat spectrum)
3. Mean value (Ee ~= 0),
4. Ljung-Box test with significant level equal to 0.05 (Pass = insufficient evidence exists to reject the null hypothesis that the signal is a white noise through LAGMAX lags)