def METHOD_NAME(r, sigma0, r_core):
    """Radial derivatives of the radial deflection angle.
    :param r: radius (angular scale)
    :param sigma0: convergence in the core
    :param r_core: core radius
    :return: dalpha/dr
    """
    return (
        sigma0
        * r_core**2
        * (
            -1.0 / r**2 * np.log((r_core**2 + r**2) / r_core**2)
            + 1 / r * r_core**2 / (r**2 + r_core**2) * 2 * r / r_core**2
        )
    )