Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!accuvax.nwu.edu!tank!zem!jeff
From: jeff@zem.uchicago.edu (Jeff Adler)
Newsgroups: comp.lang.apl
Subject: Re: Syntax for extended matrix operations
Summary: Don't try to get APL to do everything by itself.  Let it cooperate.
Keywords: APL primitives, beyond quad-divide
Message-ID: <6458@tank.uchicago.edu>
Date: 29 Nov 89 04:52:34 GMT
References: <539@s5.Morgan.COM>
Sender: news@tank.uchicago.edu
Reply-To: jeff@zaphod.uchicago.edu (Jeff Adler)
Organization: Department of Mathematics, University of Chicago
Lines: 36

In article <539@s5.Morgan.COM> amull@Morgan.COM (Andrew P. Mullhaupt) writes:
>I would like to solicit suggestions for primitives to be added to
>the APL lexicon which would update the representation of linear
>algebraic concepts...
>
>At present, the implementation is going to bail out of APL for
>almost all of this stuff. This will have the same result that 
>it had for us on APL2 on the mainframe: there, quad divide is 
>not competitive with the ESSL SVD... 
>
>P.S. Sparse and band matrix tricks, and updates (Cholesky and
>QR) would seem very desirable if they can be embedded comfortably
>in the APL syntax.

Rather than trying to get APL to do everything, wouldn't it be better
to have APL
	1. do a small number of things really well,
	2. have hooks into other programs with other capabilities?

Isn't this the point of quadNA?  If you need some fancy mathematical
functions, what's wrong with calling standard routines from a library?

In general, the issue of primitive vs defined vs external routines
applies not only to mathematical functions, but to editors, graphics,
communication, and who-knows-what-else.

My view:  If another product does something well, and if APL can
access that product through a reasonable hook, then the hook is
preferable to adding a feature to APL.

Does anyone else have any opinions on this?

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Jeff Adler				jeff@zaphod.uchicago.edu
Math Department				jeff%zaphod@gargoyle.uchicago.edu
University of Chicago			jda3@tank.uchicago.edu