Slices of the projected density shortly after the shell-crossing: comparison of LPT using ballistic approximation with Vlasov runs. The left and right groups of nine panels correspond respectively to Q1D-3SIN (top, middle, and bottom line of panels: x=−1.55×l0⁻⁴, y = −1.17×10⁻³, and z= −1.56 × 10⁻³ slice) and ANI-3SIN (x= −5.16 × 10⁻⁴, y = −2.15 × 10⁻⁴, and z= −5.47 × 10⁻⁴ slice), while the bottom group of three panels corresponds to SYM-3SIN (z= −1.17 × 10⁻⁵ slice). In each group of panels, the left, middle, and right columns give respectively the second-order LPT prediction, the tenth-order LPT prediction, and the Vlasov code measurements. Due to the symmetry of the system for SYM-3SIN, only one slice is shown for the bottom panels.