Quadtree (octree) C source code?

[Jaime Lugo]

I need samples of C source code of quadtrees to store 3-D point data.  
I was told in GIS-L that GRASS may already have this.

If you can help me, please respond directly to my e-mail address.  
I will later summarize all replies into a single message.

Thank you in advance, Jaime Lugo.
lugo at everest.hunter.cuny.edu

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