OctGPR package demo function.

Uses the model GPM to predict values, standard deviations and model derivatives in spatial points.

If requested, estimates the hyperparameters for Gaussian Process Regression (inverse length scales and relative noise) via reduced maximum likelihood, and then sets up the model for inference (prediction), storing necessary information in the structure GPM, intended for use with `gpr_predict'.

Assembles a pairwise minkowski-distance matrix for two given sets of points.

Selects a given number of RBF centers based on Lloyd's clustering algorithm.