Centre

@staticmethod
def evaluate(waveform: WaveformVariable) -> float:
    """
    Calculate the centre of a waveform. Errors if image or scalar provided.

    First, applies smoothing by taking weighted nearest and next-nearest
    neighbour contributions to  y values whose difference from their neighbours
    is more than 0.2 times the total range in y.

    The global maximum y value is then identified along with the first x positions
    either side of the peak where the y value is less than or equal to half the
    global maximum. If all values of y to one side of the peak are greater than
    half the global maximum, the position of the global maximum is used. The value
    of x at these two positions is averaged and returned.

    Note this will not be the same as the x value of the maximum, unless the data
    is symmetric.
    """
    half_max_left, half_max_right = Builtin.calculate_fwhm(waveform)
    return (half_max_left + half_max_right) / 2