| build_Sigma | Build a covariance matrix Sigma |
| build_Xchi_grad | Build chi using an analytical gradient |
| build_Xchi_numeric | Build chi via centered finite differences |
| efficiency_bound | Compute an efficiency lower bound for a given design |
| exact_design | Convert a Virtual Noise design measure into an exact design |
| plot_convergence | Plot convergence of the D-optimality criterion |
| plot_design_weights | Plot design weights over the candidate set |
| plot_efficiency | Plot efficiency diagnostic |
| virtual_noise_Dopt | Virtual Noise algorithm for D-optimal design |
| vndesign_Dopt | Main interface for constructing D-optimal designs using the Virtual Noise algorithm |