Minimum-weight perfect matching in Android system code

Heh.. I've just bounced into this article:
http://www.troodon-software.com/Algorithms/Android/2010/06/20/euclidean-bipartite-matching-multi-touch-and-android/

Check this, it's funny :) Briefly, Android's multitouch dragging uses a function that tries to solve a bipartitate matching problem (aim: track fingers). The function is a greedy algorithm being awkward sometimes. Also, a comment refers to an article in which a near-linear approximation algorithm is developed.

It's maybe just me, but..

• the greedy algorithm seems to be a quick hack and
• the complicated near-linear approximation is an overkill?

I mean.. come on, how large can n, the number of points be in this task? Most people have ten fingers only :-P at this scale, it's not the asymptotic that matters, the constants also play a significant role. So - I would go with the Hungarian method, it's easy to implement and worst-case n^3 is not a big deal at this scale.. I guess.

Bottom line: take care with the hidden constants that hide in the big O. Especially when they are comparable with the input size.