This version is different from the 08/96 version in the following:
(1) Contextual information is extracted by linear decision tree instead of
    heuristic decision tree.


Hui Cheng

08/10/97


(2) Also, model.c has been modified.  Now a look up table for exp()
    is available.   The table is on-line constructed and stores 
    values of exp() in the range of [0,-30] using 30000 bins.  The
    bins are equally spaced.
    
    08/11/97


(3) /tree_lib/sample.c also optimizes dataWeight.  But the experiment results
    shew that it improves the results on sample set not on the test
    set.  The original dataWeight is fixed.  They are 
    level=6  0.45
    level=5  0.405
    level=4  0.3645
    level=3  0.32805
	level=2  0.295245
	level=1  0.2657205
	level=0  0.23914845
