Connection Machine, eh? Now there's a blast from the past. It might intrigue you to know that our contributor specialises in quantum computing. This, I have only recently been brought to realise, holds out the promise of "connection machines" beyond our wildest imaginings.
Prime factorisation, anyone, to routinely crack the best of today's encryption? http://en.wikipedia.org/wiki/Shor%27s_algorithm But I'm at risk of giving too much away. Keep an eye on the Vector website... On Wed, May 18, 2011 at 3:05 AM, Roger Hui <[email protected]> wrote: > The cited article has the passage: > > The key adverb was not in the initial version of J. > It came in later at the request of the J user community, > notably Joey Tuttle. > > This is not consistent with what I remember. > I first saw the idea in the 1980s in > the documentation for the Connection Machine, > http://en.wikipedia.org/wiki/Connection_Machine > which had a machine instruction for doing > x f//.y for a small set of functions f and certain x's. > In any case, the October 1990 dictionary > had u/. with the same definition as now. > (The earliest public version of J, available > at APL90, was dated July 1990. > http://www.jsoftware.com/papers/J1990.htm > That version did not have "key".) > > In any case, it is true that many case of the > special code for u/. are "JKT specials", > implemented in response to code Joey posted > or in expectation that they would be useful > for what he does. > > > > ----- Original Message ----- > From: "Lettow, Kenneth" <[email protected]> > Date: Tuesday, May 17, 2011 17:37 > Subject: Re: [Jprogramming] Aggregation > To: Programming forum <[email protected]> > >> Ian, >> >> I best understood key after reading a book you edited ;-) >> >> To summarize... http://www.jsoftware.com/jwiki/Doc/Articles/Play151 >> >> All the best, >> >> Ken >> >> -----Original Message----- >> From: [email protected] >> [mailto:[email protected]] On Behalf Of Ian Clark >> Sent: Tuesday, May 17, 2011 5:09 PM >> To: Programming forum >> Subject: [Jprogramming] Aggregation >> >> I'm being lazy here. But I need a better answer than I can devil out >> myself. It occurs in a recent submission to Vector... >> >> I have an array like this (which may be unsorted, and can grow very >> large): >> >> 1 100 >> 1 100 >> 1 20 >> 1 400 >> 2 30 >> 2 200 >> 2 300 >> 33 100 >> 33 100 >> 33 100 >> >> I want to collapse it to: >> >> 1 620 >> 2 530 >> 33 300 >> >> i.e. summing over subheadings. >> The original example had A B C in place of 1 2 33, but >> numbers will >> do, to save boxing. We don't know the full set of A B C ... in >> advance. Nothing to be assumed about the first column, except it is >> +ve integers. But I'm also interested in the case where the first >> column lies in the set: i.(n) for some n>0. In other words they >> can be >> squashed up. >> >> 1. There's simply got to be a "jem" to do it. Suggestions, please. >> - Transpose the array if you wish. Box it: 1 100 ; 1 100 ; 1 20 >> ; ... >> -whatever. >> - No, of course I don't want a looping solution :) >> >> 2. What do you call this process? I call it "aggregation" -- but I >> think the name differs across disciplines. > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
