What is the fastest way to find the closest point to a given point?

Question

What is the fastest way to find closest point to the given point in data array?

For example, suppose I have an array A of 3D points (with coordinates x,

Answer 1

Its my understanding quadtree is for 2d, but you could calculate something for 3d thats is very similar. This will speed up your search, but it will require much more time to calculate the index if done on the fly. I would suggest calculating the index once then storing it. On every lookup you figure out all of the exterior quads then work your way in looking for hits... it would look like pealing an orange. The speed will greatly increase as the quads get smaller. Everything has a trade off.