Calculates the autocorrelation from a given Signal via using
    

    Parameters
    ----------
    Signal : array-like
        Array containing the signal to have the autocorrelation calculated for
    FFT : optional, bool
        Uses FFT to accelerate autocorrelation calculation, but assumes certain
        certain periodicity on the signal to autocorrelate. Zero-padding is added
        to account for this periodicity assumption.
    PyCUDA : bool, optional
       If True, uses PyCUDA to accelerate the FFT and IFFT
       via using your NVIDIA-GPU
       If False, performs FFT and IFFT with conventional
       scipy.fftpack

    Returns
    -------
    Autocorrelation : ndarray
            Array containing the value of the autocorrelation evaluated
            at the corresponding amount of shifted array-index.

def calc_autocorrelation(Signal, FFT=False, PyCUDA=False):
    """
    Calculates the autocorrelation from a given Signal via using
    

    Parameters
    ----------
    Signal : array-like
        Array containing the signal to have the autocorrelation calculated for
    FFT : optional, bool
        Uses FFT to accelerate autocorrelation calculation, but assumes certain
        certain periodicity on the signal to autocorrelate. Zero-padding is added
        to account for this periodicity assumption.
    PyCUDA : bool, optional
       If True, uses PyCUDA to accelerate the FFT and IFFT
       via using your NVIDIA-GPU
       If False, performs FFT and IFFT with conventional
       scipy.fftpack

    Returns
    -------
    Autocorrelation : ndarray
            Array containing the value of the autocorrelation evaluated
            at the corresponding amount of shifted array-index.
    """
    if FFT==True:
        Signal_padded = scipy.fftpack.ifftshift((Signal-_np.average(Signal))/_np.std(Signal))
        n, = Signal_padded.shape
        Signal_padded = _np.r_[Signal_padded[:n//2], _np.zeros_like(Signal_padded), Signal_padded[n//2:]]
        if PyCUDA==True:
            f = calc_fft_with_PyCUDA(Signal_padded)
        else:
            f = scipy.fftpack.fft(Signal_padded)
        p = _np.absolute(f)**2
        if PyCUDA==True:
            autocorr = calc_ifft_with_PyCUDA(p)
        else:
            autocorr = scipy.fftpack.ifft(p)
        return _np.real(autocorr)[:n//2]/(_np.arange(n//2)[::-1]+n//2)
    else:
        Signal = Signal - _np.mean(Signal)
        autocorr = scipy.signal.correlate(Signal, Signal, mode='full')
        return autocorr[autocorr.size//2:]/autocorr[autocorr.size//2]