def METHOD_NAME(self, x, y, theta_E, gamma, center_x=0, center_y=0):
    """
    :param x: set of x-coordinates
    :type x: array of size (n)
    :param y: set of y-coordinates
    :type y: array of size (n)
    :param theta_E: Einstein radius of lens
    :type theta_E: float.
    :param gamma: power law slope of mass profile
    :type gamma: <2 float
    :returns:  function
    :raises: AttributeError, KeyError
    """
    gamma = self._gamma_limit(gamma)
    x_ = x - center_x
    y_ = y - center_y
    E = theta_E / ((3.0 - gamma) / 2.0) ** (1.0 / (1.0 - gamma))
    # E = phi_E_spp
    eta = -gamma + 3
    p2 = x_**2 + y_**2
    s2 = 0.0  # softening
    return 2 * E**2 / eta**2 * ((p2 + s2) / E**2) ** (eta / 2)