Dan,
Ok, you got me: what in the world is k? I understand
the `:6 puts together the verb train to its left. I am
assuming that k produced most of the lefthand verb in the
gerund form of amend in l. But I am unclear about several
other things, including
a) is the verb train in k a fork or a hook (if it's
a fork I guess it picks up its third tine from l )?
b) in the definition of k, I understand that ties (`'s)
are needed to separate the verbs, but why is one tie on the
left and one on the right of its verb? And if there is a
third verb to make a fork, why does it not neet a tie?
c) to what is (&[)("_1) in k attaching itself or waiting
for or whatever? I guess the answer is the rest of l except
the amend, but I cannot see how.
Thank you,
On Fri, 24 Nov 2006, Dan Bron wrote:
+ JC,
+
+ Short answer:
+
+ k =: (&[) ("_1) (#/.~@:]`) (`({~ ~.)) (`:6) ~
+ l =: k (`(~.@:[)) (`]) }
+
+ f =: ^&2
+ v =: i.10
+ ind =: 3 5 3
+
+ ind f l v
+ 0 1 2 81 4 25 6 7 8 9
+
+
+ A couple of points. You say the result should be r=:1 2 81 4 25 6 7 8 9
but:
+
+ (A) (#r) is 9 whereas (#v) is 10 , so I'm assuming you forgot
+ the first element, 0 .
+
+ (B) You say f is 2^y but 2^5 is 32 , not 25 , so I assume
+ you meant y^2 (y-squared). To that end, you might want to
+ say f=: *: rather than f=: ^&2 .
+
+ Since you asked for "elegant", I decided to provide a tacit solution, to
prove that such can done in the language. If I were
+ writing this with intent of making it production code, I would probably make
it explicit. Explicit code, while not as beautiful
+ or cool, tends to be easier to read and maintain, and in complicated examples
like this, usually faster. For example, the tacit
+ code takes ~.x twice, which, in explicit code, could be calculated once and
stored in a local name.
+
+ -Dan
+
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+
(B=) <----------my "sig"
Brian Schott
Atlanta, GA, USA
schott DOT bee are eye eh en AT gee em ae eye el DOT com
http://schott.selfip.net/~brian/
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