distance between two points,  a & b  =  SQRT[   (xa-xb)^2 + (ya-
yb)^2)  ]

Define  d = the above distance squared  =  (xa-xb)^2 + (ya-yb)^2)

d =   xa^2 - 2*xa*xb + xb^2   +   ya^2 - 2*ya*yb + yb^2

d =   xa^2 - 2*xa*xb + xb^2   +   ya^2 - 2*ya*yb + yb^2

d =  ( xa^2 + xb^2 + ya^2 + yb^2 )  -  2*( xa*xb + ya*yb )

d =   first-term  -   second-term

The first-term is always positive and will always occur for all  (x,y)
pairs  ( paired off as point a & point b ).

Thus,  we want the part of the second-term in parenthesis to be as
positively large as possible !!!

Thus,  for all pairs of points   a(x,y)   &   b(x,y),   we want to
choose the  a-b pairs that cause the sum of all pairs to be as large
as possible.

ie.    If we can sum all  pairs,   a(x,y) &  b(x,y)  and   Maximize
the value of:     xa*xb + ya*yb  ,   we will have an answer!!!


So...  given a bunch of points  (xi,yi),  how do we pair them up such
that  for each pair of points,  a(x,y) & b(x,y),  we get a maximum
value of   xa*xb + ya*yb  ???

If you solve this algorithm....  I think you have a solution.   Is it
easier this way?   I'm not really sure.

Dan   :-)

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