Hello Dan;
The statement is _not_ true of ...h&]... point taken. I'm still thrown
by the late entry of the @:, which I sometimes still think of as @ . A
senior J'er moment, if you will.
Dan Bron wrote:
RM=Randy MacDonald, DB=me
RM> A good explanation for my original question is: dyadic use
RM> of (f g h &]) allows the right verb in the fork to ignore the
RM> fork's left argument.
Actually, it is the dyadic use of (f g h @:]) which allows the right verb of
a fork to ignore the fork's left argument. I
suspect Raul had a typo when he wrote &] (and he didn't notice the error
because it wouldn't be apparent unless he tried to
invoke the fork dyadically).
As an intersting aside, &] is sort of an "identity adverb", in that (u y) -: u&]
y and (x u y) -: x u&] y .
RM> (Now, where in the manual one could put that statement, I don't know.)
It's a couple of paragraphs down from the part where it says 2+3 is 5 :)
That text should be just as searchable, at least bottom-up.
DB> PPS: In x 6!:2 y I assumed x would be constrained to the positive
DB> integers. But I tried 0 (with the expected result) and negative
DB> numbers (with unexpected results)
RM> What do you see as the expected result?
Well, in advance of trying it, I expected an error. But if you said to me "if 0
(6!:2) y produces a result, what is it?", I
would have said "0" because that's how long it takes to execute a(ny) sentence
zero times. So when I saw the result (indeed, 0
), I was not surprised.
Similarly, before I tried (-x) 6!:2 y I expected a domain error (again), but
this time I was surprised when I didn't get one. I
got a very small negative result, no matter what y I used. Unlike the case
for zero, I cannot reconcile this result with the
definition of the foreign (maybe if (-x) 6!:2 y were just - (x 6!:2 y) I
could be talked into it).
I suspect the result of (-x) 6!:2 y is an unintentional artifact of its
implementation (in C code).
RM> What about fractional left arguments?
I did try fractional, infinite, and complex left arguments, and got the errors
I expected. If I had to come up with a consistent
definition with fractional x , it might be something like "time executing the
sentence (<.x) times, add to that the time it
takes to execute (x-<.x) times [by stopping the sentence partway through] and
divide the result by x ". But in practice
that's silly.
Linear interpolation? It doesn't seem that simple.
-Dan
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|\/| Randy A MacDonald | APL: If you can say it, it's done.. (ram)
|/\| ramacd <at> nbnet.nb.ca |
|\ | | The only real problem with APL is that
BSc(Math) UNBF'83 | it is "still ahead of its time."
Sapere Aude | - Morten Kromberg
Natural Born APL'er |
-----------------------------------------------------(INTP)----{ gnat }-
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