Path: utzoo!utgpu!newsserver.csri.toronto.edu!rutgers!usc!snorkelwacker!paperboy!meissner
From: meissner@osf.org (Michael Meissner)
Newsgroups: comp.arch
Subject: Re: Killer Micro II
MessageID:
Date: 31 Aug 90 14:14:18 GMT
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Inreplyto: firth@sei.cmu.edu's message of 31 Aug 90 12:19:16 GMT
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In article <8442@fy.sei.cmu.edu> firth@sei.cmu.edu (Robert Firth)
writes:
 In article aglew@dwarfs.crhc.uiuc.edu (Andy Glew) writes:
 >It sounds like Kahan is pushing for the 128 bit quad precision that
 >was dropped from the IEEE FP standard. Power to him!

 With respect, I disagree. In my opinion, there are already far to
 many engineers who use rotten numerical algorithms and trust to
 double precision and dumb luck; going to quadruple precision will
 merely encourage more of the same.

 What I think we need is hardware interval arithmetic. When the
 printout shows them beyond dispute that the choice is between
 50 bits of noise and 100 bits of noise, perhaps they'll spend
 more time on better algorithms and less time pushing for wrong
 answers faster.
Have we actually gotten to the point where we need that much precision
on a day to day basis? I seem to recall that in my numerical analysis
course 12 years ago, that it was said that your average physical
measurement only had 35 digits of accuracy. This means that any
answer received cannot be more accurate than the input. Now in order
to avoid round off error, you certainly need more digits internally,
but IEEE double gives something 1214 digits. One of the problems the
computer has introduced is too much exact numerical quantization (ie,
the often quoted statistic that the average family has 2.4 children).
It would seem to me that providing double the precision might not give
any more accurate answers.
There are probably groups that may need such extremes in precision,
but are they really enough to drive the market?

Michael Meissner email: meissner@osf.org phone: 6176218861
Open Software Foundation, 11 Cambridge Center, Cambridge, MA, 02142
Do apple growers tell their kids money doesn't grow on bushes?