Helper function for splitting 2D data into x and y component to make
        equations simpler

def unpack2D(_x):
    """
        Helper function for splitting 2D data into x and y component to make
        equations simpler
    """
    _x = np.atleast_2d(_x)
    x = _x[:, 0]
    y = _x[:, 1]
    return x, y