Author: Christos Faloutsos
Date: Feb. 2001; updated Sept. 2011

WHAT:
Implements a kd-tree,
with insertions, nearest neighbor search,
and range searches 
The coordinates are doubles.
(Improved version from the one from Maryland -
fixed a small bug with hardwired 4-dimensions)

USAGE:
   main [-d <#dimensions>]
and then follow the prompts.
* The default # of dimensions is 4.
* For range queries, the program will prompt for the low- and high- values
  for each coordinate, but then it will do nothing.

DEMO:
   make demo
to see a demo. Ignore the "Error code 3 (ignored)" message.


IMPORTANT:
   do not feed numbers greater than 'HUGE' (see 'dfn.h')

KNOWN ISSUE:
   it gives unpredictable results, if it is given a string,
   when it expects a number.

UPDATE LOG:
   - compiles under mac-osx (10.6), after replacing 'malloc.h' with 'stdlib.h'
