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From: Dave Sparks <postmaster@sisyphus.demon.co.uk>
Subject: Re: floating point comparison
Date: 1997/08/07
Date: 1997-08-07T00:00:00+00:00	[thread overview]
Message-ID: <N.19970807.idco@sisyphus.demon.co.uk> (raw)
In-Reply-To: 5sar4r$t7m$1@cnn.nas.nasa.gov


>>>>> "CLK" == Chris L Kuszmaul <fyodor@sally.nas.nasa.gov> writes:

  CLK> In article <33E74A62.53E2@pseserv3.fw.hac.com> "W. Wesley Groleau
  CLK> x4923" <wwgrol@pseserv3.fw.hac.com> writes:
  >>  What I'm trying to say is that it should be possible to come up with
  >> a few simple guidelines that cover most cases, and a guideline for
  >> identifying the cases that require a mathematician--excuse me, a
  >> numerical analyst.
  >> 


  CLK>   Fair enough. There are two basic guidlines I follow:

  CLK> ...

  CLK> Also

  CLK> 3: If you just do multiplication and division, then it is hard to mess
  CLK>    up.

But I've seen a program where one of the inputs was a temperature
in degrees Centigrade, in the range 10 to 50 with no fractional
part.  The calculated results were displayed to six decimal places -
very misleading.  The calculation was accurate, but the results
were no more precise than the inputs.

It's wrong to assume that simple numerical analysis is so easy that
anyone can do it.

-- 
Dave Sparks, Staffordshire, England




  reply	other threads:[~1997-08-07  0:00 UTC|newest]

Thread overview: 105+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
1997-07-29  0:00 floating point comparison Matthew Heaney
1997-07-30  0:00 ` Jan Galkowski
1997-07-31  0:00   ` Don Taylor
1997-07-31  0:00     ` Russ Lyttle
1997-08-01  0:00       ` W. Wesley Groleau x4923
1997-08-02  0:00         ` Robert Dewar
1997-08-02  0:00           ` Matthew Heaney
1997-08-03  0:00             ` Robert Dewar
1997-08-04  0:00           ` W. Wesley Groleau x4923
1997-08-05  0:00             ` Jan-Christoph Puchta
1997-08-05  0:00               ` W. Wesley Groleau x4923
1997-08-05  0:00                 ` Samuel Mize
1997-08-06  0:00                 ` Chris L. Kuszmaul
1997-08-07  0:00                   ` Dave Sparks [this message]
1997-08-08  0:00                     ` Robert Dewar
1997-08-08  0:00                     ` Mark Eichin
1997-08-08  0:00                     ` Jan-Christoph Puchta
1997-08-09  0:00                       ` Robert Dewar
1997-08-10  0:00                       ` Lynn Killingbeck
     [not found]                   ` <5sbb90$qsc@redtail.cruzio.com>
     [not found]                     ` <5scugs$jdc$1@cnn.nas.nasa.gov>
1997-08-07  0:00                       ` Robert Dewar
1997-08-08  0:00                     ` Gerhard Heinzel
1997-08-08  0:00                       ` Daniel Villeneuve
1997-08-08  0:00                       ` schlafly
1997-08-09  0:00                       ` Robert Dewar
1997-08-09  0:00                         ` David Ullrich
1997-08-10  0:00                           ` Robert Dewar
1997-08-16  0:00                             ` Andrew V. Nesterov
1997-08-18  0:00                               ` Robert Dewar
1997-08-19  0:00                                 ` Hans Olsson
1997-08-19  0:00                                 ` Jim Carr
1997-08-21  0:00                                   ` Christian Bau
1997-08-21  0:00                                     ` Jim Carr
1997-08-21  0:00                                       ` Robert Dewar
1997-08-22  0:00                                         ` Jim Carr
1997-08-22  0:00                                           ` Robert Dewar
1997-08-23  0:00                                             ` Jim Carr
1997-08-24  0:00                                               ` Robert Dewar
     [not found]                                                 ` <5u4eq6$30b$1@news.lth.se>
1997-08-29  0:00                                                   ` Robert Dewar
1997-09-01  0:00                                                     ` Chris RL Morgan
1997-08-29  0:00                                                 ` Andrew V. Nesterov
1997-08-29  0:00                                                   ` Robert Dewar
     [not found]                                                     ` <340DF1DD.2736@iop.com>
1997-09-07  0:00                                                       ` Get_Immediate Robert Dewar
1997-09-07  0:00                                                       ` Get_Immediate Robert Dewar
1997-09-08  0:00                                                       ` Get_Immediate J Giffen
1997-09-01  0:00                                                 ` floating point comparison Jim Carr
     [not found]                                                   ` <checkerEFx6xI.FCM@netcom.com>
1997-09-03  0:00                                                     ` Chris L. Kuszmaul
1997-09-05  0:00                                                       ` Malome Khomo
1997-09-07  0:00                                                       ` Robert Dewar
1997-09-05  0:00                                                   ` Robert Dewar
1997-09-10  0:00                                                     ` Jim Carr
1997-09-12  0:00                                                       ` Robert Dewar
1997-09-15  0:00                                                         ` James Pauley
1997-09-16  0:00                                                           ` Robert Dewar
1997-08-23  0:00                                         ` W. Wesley Groleau x4923
1997-08-23  0:00                                           ` Robert Dewar
1997-08-30  0:00                                 ` Paul Eggert
1997-08-06  0:00                 ` Robert Dewar
1997-08-07  0:00                   ` Shmuel (Seymour J.) Metz
1997-08-08  0:00                     ` Peter Shenkin
1997-08-09  0:00                       ` Albert Y.C. Lai
1997-08-06  0:00             ` Robert Dewar
1997-08-07  0:00               ` Dr. Rex A. Dwyer
     [not found]               ` <33E8DFF6.6F44@pseserv3.fw.hac.com>
1997-08-07  0:00                 ` Robert Dewar
     [not found]                 ` <33EA1251.3466@link.com>
     [not found]                   ` <33EA46CC.226@pseserv3.fw.hac.com>
1997-08-08  0:00                     ` Christian Bau
1997-08-12  0:00                     ` Martin Tom Brown
1997-08-23  0:00                       ` W. Wesley Groleau x4923
1997-08-23  0:00                         ` Robert Dewar
1997-09-05  0:00                         ` Robert I. Eachus
1997-09-06  0:00                           ` schlafly
1997-09-09  0:00                             ` Robert Dewar
1997-09-07  0:00                           ` M. J. Saltzman
1997-09-11  0:00                           ` Robin Rosenberg
1997-08-06  0:00             ` Robert Dewar
     [not found]               ` <33E8E3E1.17EA@pseserv3.fw.hac.com>
     [not found]                 ` <5sbgpk$q0n$1@goanna.cs.rmit.edu.au>
1997-08-07  0:00                   ` Robert Dewar
     [not found]                     ` <33FE4603.1B6B@pseserv3.fw.hac.com>
1997-08-23  0:00                       ` Robert Dewar
1997-08-08  0:00                   ` W. Wesley Groleau x4923
1997-08-07  0:00             ` Do-While Jones
1997-08-03  0:00         ` Brian Rogoff
1997-08-03  0:00           ` Robert Dewar
1997-07-30  0:00 ` Robert Dewar
1997-07-30  0:00   ` Matthew Heaney
1997-07-31  0:00     ` Jim Carr
1997-07-30  0:00   ` Matthew Heaney
1997-07-31  0:00     ` Samuel Mize
1997-07-31  0:00     ` Martin Tom Brown
1997-07-31  0:00     ` Bob Binder  (remove .mapson to email)
1997-07-31  0:00       ` Robert Dewar
1997-08-01  0:00         ` Dale Stanbrough
1997-08-04  0:00         ` Paul Eggert
1997-08-06  0:00           ` Robert Dewar
1997-08-14  0:00             ` Paul Eggert
1997-08-01  0:00       ` user
1997-08-02  0:00         ` Peter L. Montgomery
1997-08-04  0:00           ` W. Wesley Groleau x4923
1997-08-05  0:00             ` Bob Binder  (remove .mapson to email)
1997-08-02  0:00         ` Lynn Killingbeck
1997-08-03  0:00           ` Bob Binder  (remove .mapson to email)
1997-08-03  0:00             ` Charles R. Lyttle
1997-08-03  0:00           ` Robert Dewar
1997-07-31  0:00     ` Robert Dewar
1997-08-02  0:00     ` Lynn Killingbeck
1997-07-31  0:00   ` Gerald Kasner
1997-07-31  0:00     ` Robert Dewar
1997-08-02  0:00 ` Michael Sierchio
1997-08-08  0:00 ` floating point conversions Mark Lusti
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