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From: karsh@geowhiz.UUCP (Bruce Karsh)
Newsgroups: net.physics
Subject: Re: Quickly Computing Quarks (Science News, VOL. 128)
Message-ID: <230@geowhiz.UUCP>
Date: Thu, 22-Aug-85 01:00:57 EDT
Article-I.D.: geowhiz.230
Posted: Thu Aug 22 01:00:57 1985
Date-Received: Sat, 24-Aug-85 19:16:58 EDT
References: <509@sri-arpa.ARPA>
Reply-To: karsh@geowhiz.UUCP (Bruce Karsh)
Organization: UW Madison, Geology Dept.
Lines: 32

In article <509@sri-arpa.ARPA> WBD.TYM@OFFICE-2.ARPA writes:
>From:  William Daul / McDonnell-Douglas / APD-ASD  
>
>A team of physicists 
>will soon take over a specially built computer designed to solve a single 
>physics problem.   According to an IBM official, this computer is supposed to 
>take less than a year to solve a provblem that would take a CRAY-1 
>supercomputer more than 300 years to do.
>The IBM machine, developed at the Thomas J. Watson Research Center in Yorktown 
>Heights, N.Y., consists of an array of 576 processors, each one capable of 20 
>million "floating point" operations per second (equivalent to multiplying two 
>decimal numbers 20 million times).  In contrast, a typical personal computer 
>performs 1,000 or so such operations per second.  When all the processors are 
>working in parallel, each one handling a small part of a computation, the IBM 
>computer can handle more than 10 billion floating point operations per second.

Does anybody know how you would go about retaining significant digits
in a computation like this?  If you figure there there will be about
10**9 round off errors per second accumulating for one year, there must
be some plans for designing the calculations to be *EXTREMELY*
insensitive to round off problems.

How is this going to work?  Is there literature on this subject?


-- 

Bruce Karsh
U. Wisc. Dept. Geology and Geophysics
1215 W Dayton, Madison, WI 53706
(608) 262-1697
{ihnp4,seismo}!uwvax!geowhiz!karsh