Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!usc!snorkelwacker!paperboy!meissner From: meissner@osf.org (Michael Meissner) Newsgroups: comp.arch Subject: Re: Killer Micro II Message-ID: Date: 31 Aug 90 14:14:18 GMT References: <527@llnl.LLNL.GOV> <603@array.UUCP> <2482@l.cc.purdue.edu> <2868@inews.intel.com> <8442@fy.sei.cmu.edu> Sender: news@OSF.ORG Organization: Open Software Foundation Lines: 38 In-reply-to: firth@sei.cmu.edu's message of 31 Aug 90 12:19:16 GMT 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 3-5 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 12-14 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: 617-621-8861 Open Software Foundation, 11 Cambridge Center, Cambridge, MA, 02142 Do apple growers tell their kids money doesn't grow on bushes?