| density_g_model | The l_1 to l_4 derivative from the g-modeling method |
| density_LS | log-density derivatives-parametric approach |
| density_PLS | Penalized least-squares method in Du and Hu (2022) |
| EB_CS | Main function used in the paper (Du and Hu, 2022) |
| predictive_recursion | Predictive recursion by Newton (2002) |