NEIGHBOR function in RPL

[Dave Britten]

There's probably a more elegant way of doing this, but there's some really weird guard digit stuff going on here.

(Try this: 1 5E-12 + 6E-12 + 5E-12 + 5E-12 +. The results are... peculiar.)

Stupid special cases to the rescue. This seems to be working...

Code:

\<< \-> X Y
  \<< X MANT IF DUP 1 SAME Y X < AND THEN -12 ALOG - ELSE
    Y X - SIGN -11 ALOG * + END
    X XPON ALOG *
\>>