Absolute value of the difference between the expected and numerical results on J₂ × 10⁶ for different spacings of the spheroids with N = 512. Lin, squ and cub are repartitions of spheroids following a power law of exponent 1, 2 or 3, respectively; exp^{γ = 8} is the exponential repartition with our favored value γ = 8. HM is the method exposed in HM16, explained in Appendix C.2. The subscript 1 means that the first layer has a non-0 density while the subscript 0 means zero density in the first layer.