0. The use of terms from natural languages (noun, verb, adverb, etc.) is an
extended and useful metaphor. See section 4 of *Some Exercises in APL
Language Design <http://www.jsoftware.com/papers/APLDesignExercises.htm>*.
1. There is a way to do the common inner product *./ .= ("and dot equals")
much more efficiently using i., made possible by the "item" (major cell)
definition of i. . See section 12 of *Index-Of, a 30-Year Quest
<http://www.jsoftware.com/papers/indexof/indexof.htm>*. In over 45 years
of APL systems no one I know of thought to implement and-dot-equals using
index-of. They might have with the extended definition of i. (the J
definition).
2. Inner product itself can be stated using the rank operator, computed
differently from the conventional "row-by-column". See *Inner Product --
An Old/New Problem <http://www.jsoftware.com/papers/innerproduct/>*. This
alternative computation, "row-at-a-time", can be faster than
"row-by-column" by a factor of 10 or more.
On Mon, Oct 16, 2017 at 2:22 AM, Stuart Baker <[email protected]>
wrote:
> Pretty much an outsider here - it's a long time since I wrote any code in
> J or any other language. What occurs to me, as it often used to when I was
> actually programming, is that J (and APL) are much more language-like than
> all the others. Leaving aside the adoption of noun/verb/adverb etc
> terminology, superficial but nicely provocative, the characteristic of, I
> guess, all natural languages is that there are (a) genuinely different ways
> of saying (functionally identical) things, and (b) there are always
> genuinely novel expressions arising, in written or spoken form. This is not
> in my experience true of any programming 'languages' other than the J/APL
> family. All expressions seem to boil down to variations of the same set -
> variations only distinguished by superficial naming, and/or their
> application in the 'real' world. I always loved the thought that I (or more
> likely someone else) might someday discover a startlingly novel
> inner-product that actually addressed some problem, and constituted a
> genuine invention of thought. As a non-mathematician, I make way happily to
> those who would say all the distinct fundamental pathways through the
> expressiveness of J have been explored, or at least elaborated. However, it
> was that perceived richness that first drew me to the languages, and
> continues to be a unique and admirable quality for me.
>
>
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
