Newsgroups: comp.lang.apl
Path: utzoo!utgpu!news-server.csri.toronto.edu!torsqnt!jtsv16!blister!itcyyz!yrloc!rbe
From: rbe@yrloc.ipsa.reuter.COM (Robert Bernecky)
Subject: Re: WANTED: a way to sort array so each column i
Message-ID: <1991Apr19.193342.20318@yrloc.ipsa.reuter.COM>
Reply-To: rbe@yrloc.ipsa.reuter.COM (Robert Bernecky)
Organization: I P Sharp Associates, Toronto
References: <31931@usc> <13APR91.22583472@uc780.umd.edu> <WEG.91Apr14120440@convx1.convx1.ccit.arizona.edu> <14APR91.18400456@uc780.umd.edu> <1991Apr17.151913.4891@csrd.uiuc.edu>
Date: Fri, 19 Apr 91 19:33:42 GMT

In article <1991Apr17.151913.4891@csrd.uiuc.edu> jaxon@sp27.csrd.uiuc.edu (Greg P. Jaxon) writes:
>cs450a03@uc780.umd.edu writes:
>
>>>Incidentally, how does one write this function in APL2?
>> you could write a function F to sort vector
>>then do:
>>         transpose mix  F each  split[quadIO] array
>>You might be able to do something with mix and brackets to avoid the
>>transpose, but I don't know what exactly, off the top of my head.
>>Raul Rockwell
>

This seems to reflect the basic difference in theology between APL2 and 
the SHARP APL/J world:

APL2 uses split or partitioned enclose to create an array of arrays, 
applies some operation at one level down to each of those results, then
uses mix or disclose to restore the data to its original depth.

J and SAPL consider the operation to be defined on arrays of some particular
rank, and then extends to higher rank arrays in a uniform manner. The Rank
conjunction is used with these operations, when needed, to modidy that
behavior. 

Effectively, J applies a different operation to the same data.

APL2 applies the same function to different data.

I believe that J is going to be easier to optimize for better performance
in this area, having done some of that optimization for SHARP APL in
the dim past.


Robert Bernecky      rbe@yrloc.ipsa.reuter.com  bernecky@itrchq.itrc.on.ca 
Snake Island Research Inc  (416) 368-6944   FAX: (416) 360-4694 
18 Fifth Street, Ward's Island
Toronto, Ontario M5J 2B9 
Canada
