Oops this belongs here. . .
Hi Devon, Tama and I just flew up toNYC. I had time to take my eyes off
tacit and found this. There was a white book about education for APL. I
can,t remember the name. Ken and three or four teachers put it together one
summer at IBM. It might have something.Linda
Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Devon McCormick <
[email protected]> Date: 9/5/18 4:04 PM (GMT-05:00) To: J-programming
forum <[email protected]> Subject: Re: [Jprogramming] Using rank
to avoid looping - reference?
Thanks for all the responses.
Raul: you are right as array programming without rank also lets you avoid
loops; rank refines how one slices an array.
What I'm looking for are works I can cite on the Wikipedia page. As it
stands, it's too free-form and and too original which is not what the
Wikipedia guidelines specify. I will resort to things like the J site or a
Mathematica help page but I'm concerned about the potential drawbacks of
citing a web-page that may change or disappear as opposed to a published
work. Also, now that I look at the Mathematica page for "map", it does not
seem to be a good fit as their map looks very vectorish, not generally
array-oriented, so it's not clear that rank applies. I may have to remove
these claims unless I find a more apt source.
Pascal: thanks for pointing out the problem with /. I'll fix that.
Part of the problem is that most other languages' references to "array"
really mean "numeric vector", at least in my experience.
On Wed, Sep 5, 2018 at 2:52 PM 'Pascal Jasmin' via Programming <
[email protected]> wrote:
the wikipage mislabels the / operator as map as well (it is in fact a
reduce operator)
The functional map function replaces a "for each" loop. Rank is very
closely tied to this, with the addition of specifying the
size/slice/scope
of the "each element" group
On Wednesday, September 5, 2018, 1:56:33 p.m. EDT, Cliff Reiter <
[email protected]> wrote:
From Mathematica help:
Map (Built-in Symbol)
Map[f, expr] or f /@ expr applies f to each element on the first level
in expr. Map[f, expr, levelspec] applies f to parts of expr specified by
levelspec. Map[f] represents\[Ellipsis]
On 9/5/2018 10:58 AM, devonmcc wrote:
I am trying to bring the Wikipedia page on "rank (J programming
language)" into compliance with the guidelines by inserting more inline
references but am stumped by that page's initial assertion that rank is a
generalization of looping, as well as the subsequent claims about rank
generalizing "map" and "maplist".
Searches for a word like "rank" bring up many irrelevant hits even when
included with programming-specific terms. Also, the best reference I
have
found so far - www.ccs.neu.edu/home/jrslepak/typed-j.pdf - uses language
like "...a form of rank...which renders much of a program's control
structure implicit by lifting base operators to higher-dimensional array
structures." I will have to include this in the references to use it but
was hoping to find an older document, preferably one already in the
references, but have been stymied by the lack of explicit reference to
avoiding loops by using rank because it seems so obvious that it is only
implied.
In any case, a reference to the assertions about "map" and such would
also be appreciated.
Thanks,
Devon
Sent from my Verizon, Samsung Galaxy smartphone
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--
Devon McCormick, CFA
Quantitative Consultant
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