Path: utzoo!utgpu!water!watmath!clyde!att-cb!att-ih!alberta!cdshaw
From: cdshaw@alberta.UUCP (Chris Shaw)
Newsgroups: comp.arch
Subject: Re: FORTRAN Horror
Message-ID: <1162@pembina.UUCP>
Date: 27 Mar 88 04:56:01 GMT
References: <1135@pembina.UUCP> <28200126@ccvaxa>
Reply-To: cdshaw@pembina.UUCP (Chris Shaw)
Organization: U. of Alberta, Edmonton, Alberta, Canada
Lines: 33

Sorry about the time lag... too much work on the plate...

In article <28200126@ccvaxa> aglew@ccvaxa.UUCP writes:
>
>..> Chris Shaw on SPARSPAK
>
>(1) Is it possible to give out your C-SPARSPAK?

It isn't mine to give. You want to talk to Dr. J. Alan George at the 
U of Tenessee, or Oak Ridge N.L., or U of Waterloo (pick one, last I heard,
he had some ceremonial position at Waterloo).

Possible addresses: Mike Heath -> mth@ornl-msr
Alan George -> jageorge@waterloo or jag@ornl-msr

>(2) Do you have any ideas as to what a (vector) processor
>    can do to make sparse matrix codes run faster?

Lisper's answer was basically right on this one. The subtlety that I don't
think he mentioned is that sparse matrix code is basically a major
exercise in data management. In other words, you squeeze out the zeros.
This would be easy except that when you start the calculations, you cause
some of these zeros to be filled in.

So what you do is reserve space for all the fill-ins beforehand, then do the
calculations. It's vectorizeable if you manage your data right, and you
probably don't need scatter/gather. However, the verctors are likely to be
short, which may not be such a win. 

-- 
Chris Shaw    cdshaw@alberta.UUCP (via watmath, ihnp4 or ubc-vision)
University of Alberta
CatchPhrase: Bogus as HELL !