def METHOD_NAME(self, R, amp, sigma):
    """
    :param R:
    :param amp:
    :param sigma:
    :return:
    """
    sigma_x, sigma_y = sigma, sigma
    A = amp / (2 * np.pi * sigma_x * sigma_y)
    c = 1.0 / (2 * sigma_x * sigma_y)
    result = (
        1.0
        / (2 * c)
        * (
            -R * np.exp(-c * R**2)
            + scipy.special.erf(np.sqrt(c) * R) * np.sqrt(np.pi / (4 * c))
        )
    )
    return result * A * 4 * np.pi