And another algorithm I'm looking for: A free C/C++ implementation of the average distance to nearest neighbour problem.
So basically I have a cloud of points in 3D and I want the average over the distances between all points and their respective nearest neighbours. So easiest way to do this would be to find the nearest neighbour for every point, calculate the distance of that neighbour to the point, and devide the sum of those distances by the number of points. However, there are much better algorithms, as this has much redundancy and approximates run even faster. I'm looking for a free C/C++ implementation of those better algorithms.
An ε-Approximate if fine.