I'm trying to take a set of numbers and find a list of all the
possible (positive) results of adding or subtracting those numbers. So
for 1 4 9 the result would be 4 6 12 14.
I spent some time trying to figure out how to come up with a verb that
could be inserted between each atom of the list that would get the
positive and negative of the argument to its right, add that to each
item of the list to its left, get the nub of that list, and then
continue on, but that didn't work.
Then I happened to try (+,-)/ to see what it would do, and low and
behold it seemed to generate most of the possible values (?) For
example:
(+,-)/ 1 2 3
6 0 _4 2
I have no idea what is going on here. Can anyone explain? In short
sentences of small words ;-)
The train I ended up with is shown below. It seems to work, but is it
right?
/:~ ~. | (+,-)/ 3 6 11 12
2 4 8 10 14 20 26 32
Also (sorry to still be tossing out newbie questions) if this is
right, how do I package it up so I can use it:
v=: /:~ ~. | (+,-)/
v 1 2 3 4
|length error: v
Thanks -- still having fun!
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