First-order structure function (q = 1) of the artificial MDPL2 density field. The red dots show S₁^ρ(r) = ⟨|δ(x + r)−δ(x)|⟩ computed from 3.2 × 10⁷ pairs, and the blue dots from 6.4 × 10⁷ pairs. Two regimes appear: (i) a limited small-scale range with slope ∼0.25 − 0.30, and (ii) a broader regime starting at 40 − 50 Mpc h⁻¹ with slope ≈0. The red lines mark these regimes; the blue lines show linear fits to the 6.4 × 10⁷ pair sample (the first has slope 0.26). The close overlap of the two estimates indicates convergence for ≳3.2 × 10⁷ sampled pairs.