Re: Computer arithmetic problems worth exploring

From	Tom Gardner <spamjunk@blueyonder.co.uk>
Newsgroups	comp.arch
Subject	Re: Computer arithmetic problems worth exploring
References	<Xns9E976A31E575bubbachipsetone@130.133.4.11> <5aafeac2-a223-4173-adaf-8d2ebc535f20@o7g2000prn.googlegroups.com> <bc8e9ba6-c3f4-410d-80f0-2790c4efa714@w6g2000vbo.googlegroups.com> <vir9s650jhccr639kr9s3bofe6rqc9ih1t@4ax.com> <iq30p4$uff$1@gosset.csi.cam.ac.uk>
Message-ID	<vi9xp.6$lm2.1@newsfe17.ams2> (permalink)
Organization	virginmedia.com
Date	2011-05-07 11:38 +0100

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nmm1@cam.ac.uk wrote:
> As you know,
> but very few do, consistency and repeatability are not closely
> associated with accuracy.

Regrettably that kind of misapprehension is not limited to
programmers: engineers (and especially engineers-mutated-into-managers)
are also prone to it. I've lost count of the times I've been asked for
"accurate measurements" (or similar), with zero comprehension of the
inadequacy of that type of question.

When it is important, i.e. typically a manager, I take the time to
tell them the story of a very expensive attenuation test set with a
repeatability of 0.001dB - even though its accuracy was only 0.1dB.

It usually takes a couple of minutes to be sure that they haven't
misheard and have understood the 100-fold "discrepancy". Unless they
are especially clueless, they are sufficiently interested to learn that
it was use for testing the attenuation of transatlantic telephone
cables as a function of temperature. Since the cable drums were rather
large, it took a week in an oven to change the cable's temperature,
and the attenuation only changed by a small fraction of a dB. Nobody
cared what the actual attenuation was - only the change in attenuation.

And don't get me started on what I once saw inside an application for
a financial payments system. Basically it was frig the floating point
arithmetic until the small number of specified unit tests passed.
I damn near resigned on the spot.

Thread

Re: Computer arithmetic problems worth exploring George Neuner <gneuner2@comcast.net> - 2011-05-07 03:06 -0400
  Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-07 09:44 +0100
    Re: Computer arithmetic problems worth exploring Tom Gardner <spamjunk@blueyonder.co.uk> - 2011-05-07 11:38 +0100
      Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-07 12:21 +0100
        Re: Computer arithmetic problems worth exploring Tom Gardner <spamjunk@blueyonder.co.uk> - 2011-05-07 13:47 +0100
          Re: Computer arithmetic problems worth exploring Quadibloc <jsavard@ecn.ab.ca> - 2011-05-07 09:55 -0700
            Re: Computer arithmetic problems worth exploring Tom Gardner <spamjunk@blueyonder.co.uk> - 2011-05-07 19:27 +0100
              Re: Computer arithmetic problems worth exploring Quadibloc <jsavard@ecn.ab.ca> - 2011-05-07 13:54 -0700
                Re: Computer arithmetic problems worth exploring George Neuner <gneuner2@comcast.net> - 2011-05-09 13:38 -0400
                Re: Computer arithmetic problems worth exploring Robert A Duff <bobduff@shell01.TheWorld.com> - 2011-05-10 12:40 -0400
                Re: Computer arithmetic problems worth exploring Terje Mathisen <"terje.mathisen at tmsw.no"> - 2011-05-10 20:32 +0200
            Re: Computer arithmetic problems worth exploring torbenm@diku.dk (Torben Ægidius Mogensen) - 2011-05-09 13:42 +0200
    Re: Computer arithmetic problems worth exploring Quadibloc <jsavard@ecn.ab.ca> - 2011-05-07 04:26 -0700
      Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-07 12:13 +0100
  Re: Computer arithmetic problems worth exploring "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-05-07 14:59 -0700
    Re: Computer arithmetic problems worth exploring George Neuner <gneuner2@comcast.net> - 2011-05-09 14:14 -0400
      Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-09 20:38 +0100
      Re: Computer arithmetic problems worth exploring "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-05-09 13:55 -0700
        Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-10 09:05 +0100
          Re: Computer arithmetic problems worth exploring Jason Riedy <jason@lovesgoodfood.com> - 2011-05-10 13:24 -0400
            Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-10 18:41 +0100
            Re: Computer arithmetic problems worth exploring "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-05-11 13:56 -0700
            Re: Computer arithmetic problems worth exploring "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-05-11 14:04 -0700
            Re: Computer arithmetic problems worth exploring "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-05-11 14:06 -0700
          Re: Computer arithmetic problems worth exploring "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-05-11 13:55 -0700
            Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-11 22:15 +0100
              Re: Computer arithmetic problems worth exploring Tom Gardner <spamjunk@blueyonder.co.uk> - 2011-05-12 20:52 +0100
                Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-12 20:20 +0100
                Re: Computer arithmetic problems worth exploring Quadibloc <jsavard@ecn.ab.ca> - 2011-05-12 14:55 -0700
                Re: Computer arithmetic problems worth exploring Terje Mathisen <"terje.mathisen at tmsw.no"> - 2011-05-13 12:25 +0200
                Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-13 11:18 +0100
                Re: Computer arithmetic problems worth exploring "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-05-14 13:19 -0700
                Re: Computer arithmetic problems worth exploring Quadibloc <jsavard@ecn.ab.ca> - 2011-05-14 19:11 -0700
              Re: Computer arithmetic problems worth exploring "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-05-12 20:08 -0700
            Re: Computer arithmetic problems worth exploring Jason Riedy <jason@lovesgoodfood.com> - 2011-05-12 23:54 -0400
        Re: Computer arithmetic problems worth exploring George Neuner <gneuner2@comcast.net> - 2011-05-12 01:08 -0400
          Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-12 09:27 +0100
            Re: Computer arithmetic problems worth exploring Quadibloc <jsavard@ecn.ab.ca> - 2011-05-12 05:41 -0700
              Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-12 13:22 +0100
                Re: Computer arithmetic problems worth exploring Quadibloc <jsavard@ecn.ab.ca> - 2011-05-12 07:22 -0700
                Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-12 14:58 +0100
                Re: Computer arithmetic problems worth exploring MitchAlsup <MitchAlsup@aol.com> - 2011-05-12 09:23 -0700
                Non-constant initializers Fred the Freshwater Catfish <usenet.fred@bdtd.invalid> - 2011-05-12 22:59 +0000
                Re: Non-constant initializers Ian Collins <ian-news@hotmail.com> - 2011-05-13 11:07 +1200
                Re: Non-constant initializers Fred the Freshwater Catfish <usenet.fred@bdtd.invalid> - 2011-05-12 23:17 +0000
                Re: Non-constant initializers Ian Collins <ian-news@hotmail.com> - 2011-05-13 11:20 +1200
                Re: Non-constant initializers Fred the Freshwater Catfish <usenet.fred@bdtd.invalid> - 2011-05-12 23:30 +0000
                Re: Non-constant initializers Ian Collins <ian-news@hotmail.com> - 2011-05-13 11:34 +1200
                Re: Non-constant initializers Keith Thompson <kst-u@mib.org> - 2011-05-12 16:52 -0700
                Re: Non-constant initializers Fred the Freshwater Catfish <usenet.fred@bdtd.invalid> - 2011-05-14 00:13 +0000
                Re: Non-constant initializers kym@kymhorsell.com - 2011-05-14 01:54 +0000
                Re: Non-constant initializers Columbus sailed the ocean China Blue <chine.bleu@yahoo.com> - 2011-05-14 01:07 -0700
                Re: Non-constant initializers kym@kymhorsell.com - 2011-05-14 09:22 +0000
                Re: Non-constant initializers Fred the Freshwater Catfish <usenet.fred@bdtd.invalid> - 2011-05-14 17:14 +0000
                Re: Non-constant initializers Fred the Freshwater Catfish <usenet.fred@bdtd.invalid> - 2011-05-14 00:11 +0000
                Re: Non-constant initializers Columbus sailed the ocean China Blue <chine.bleu@yahoo.com> - 2011-05-12 16:15 -0700
                Re: Non-constant initializers Fred the Freshwater Catfish <usenet.fred@bdtd.invalid> - 2011-05-12 23:28 +0000
                Re: Non-constant initializers Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-05-12 18:01 -0600
                Re: Non-constant initializers Keith Thompson <kst-u@mib.org> - 2011-05-12 18:15 -0700
                Re: Non-constant initializers Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-05-12 22:56 -0600
                Re: Non-constant initializers Seebs <usenet-nospam@seebs.net> - 2011-05-13 05:18 +0000
                Re: Non-constant initializers Fred the Freshwater Catfish <usenet.fred@bdtd.invalid> - 2011-05-13 23:57 +0000
            Re: Computer arithmetic problems worth exploring "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-05-12 20:20 -0700
              Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-13 09:48 +0100
                Re: Computer arithmetic problems worth exploring Terje Mathisen <"terje.mathisen at tmsw.no"> - 2011-05-13 12:55 +0200
                Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-13 11:25 +0100
                Re: Computer arithmetic problems worth exploring MitchAlsup <MitchAlsup@aol.com> - 2011-05-13 08:57 -0700
                Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-13 16:42 +0100
                Re: Computer arithmetic problems worth exploring MitchAlsup <MitchAlsup@aol.com> - 2011-05-13 13:17 -0700
                Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-13 21:03 +0100
                Re: Computer arithmetic problems worth exploring Terje Mathisen <"terje.mathisen at tmsw.no"> - 2011-05-14 06:43 +0200
                Re: Computer arithmetic problems worth exploring Tom Gardner <spamjunk@blueyonder.co.uk> - 2011-05-14 06:55 +0100
                Re: Computer arithmetic problems worth exploring "Ken Hagan" <k.hagan@thermoteknix.com> - 2011-05-17 12:59 +0100
                Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-17 12:44 +0100
                Re: Computer arithmetic problems worth exploring Tom Gardner <spamjunk@blueyonder.co.uk> - 2011-05-17 14:07 +0100
                Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-17 17:20 +0100
                Re: Computer arithmetic problems worth exploring "Ken Hagan" <k.hagan@thermoteknix.com> - 2011-05-17 15:03 +0100
                Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-14 08:43 +0100
                Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-14 09:17 +0100
                Re: Computer arithmetic problems worth exploring Stephen Fuld <SFuld@alumni.cmu.edu.invalid> - 2011-05-14 09:04 -0700
                Re: Computer arithmetic problems worth exploring "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-05-14 17:00 -0700
                Re: Computer arithmetic problems worth exploring "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-05-14 16:58 -0700
                Re: Computer arithmetic problems worth exploring Quadibloc <jsavard@ecn.ab.ca> - 2011-05-14 19:07 -0700
                Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-15 09:40 +0100
                Re: Computer arithmetic problems worth exploring Terje Mathisen <"terje.mathisen at tmsw.no"> - 2011-05-16 11:05 +0200
                Re: Computer arithmetic problems worth exploring Quadibloc <jsavard@ecn.ab.ca> - 2011-05-16 06:44 -0700
                Re: Computer arithmetic problems worth exploring mac <acolvin@efunct.com> - 2011-05-19 20:17 +0000
                Re: Computer arithmetic problems worth exploring Quadibloc <jsavard@ecn.ab.ca> - 2011-05-19 15:20 -0700
                Re: Computer arithmetic problems worth exploring George Neuner <gneuner2@comcast.net> - 2011-05-19 18:51 -0400
                Re: Computer arithmetic problems worth exploring Petter Gustad <newsmailcomp6@gustad.com> - 2011-05-20 08:01 +0200
                Re: Computer arithmetic problems worth exploring "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-05-20 15:09 -0700
                Re: Computer arithmetic problems worth exploring Terje Mathisen <"terje.mathisen at tmsw.no"> - 2011-05-20 08:54 +0200
                Re: Computer arithmetic problems worth exploring "Ken Hagan" <k.hagan@thermoteknix.com> - 2011-05-23 11:11 +0100
                Re: Computer arithmetic problems worth exploring George Neuner <gneuner2@comcast.net> - 2011-05-23 18:20 -0400
                Re: Computer arithmetic problems worth exploring Morten Reistad <first@last.name> - 2011-06-03 08:21 +0200
                Re: Computer arithmetic problems worth exploring Stephen Fuld <SFuld@alumni.cmu.edu.invalid> - 2011-05-19 13:31 -0700
                Re: Computer arithmetic problems worth exploring Stephen Fuld <SFuld@alumni.cmu.edu.invalid> - 2011-05-16 09:05 -0700
                Re: Computer arithmetic problems worth exploring Terje Mathisen <"terje.mathisen at tmsw.no"> - 2011-05-16 22:37 +0200
                Re: Computer arithmetic problems worth exploring Stephen Fuld <SFuld@alumni.cmu.edu.invalid> - 2011-05-18 23:16 -0700
                Re: Computer arithmetic problems worth exploring ChrisQ <meru@devnull.com> - 2011-05-17 17:10 +0100
                Re: Computer arithmetic problems worth exploring Tom Gardner <spamjunk@blueyonder.co.uk> - 2011-05-17 17:27 +0100
                Re: Computer arithmetic problems worth exploring ChrisQ <meru@devnull.com> - 2011-05-17 23:08 +0100
                Re: Computer arithmetic problems worth exploring Tom <tggzzz@blueyonder.co.uk> - 2011-05-17 22:37 +0000
                Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-18 09:25 +0100
                Re: Computer arithmetic problems worth exploring Quadibloc <jsavard@ecn.ab.ca> - 2011-05-18 06:25 -0700
                Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-18 14:06 +0100
                Re: Computer arithmetic problems worth exploring Tom Gardner <spamjunk@blueyonder.co.uk> - 2011-05-18 19:23 +0100
                Re: Computer arithmetic problems worth exploring Quadibloc <jsavard@ecn.ab.ca> - 2011-05-18 13:48 -0700
                Re: Computer arithmetic problems worth exploring Andrew Reilly <areilly---@bigpond.net.au> - 2011-05-19 00:29 +0000
                Re: Computer arithmetic problems worth exploring "Ken Hagan" <k.hagan@thermoteknix.com> - 2011-05-19 13:12 +0100
                Re: Computer arithmetic problems worth exploring Stephen Fuld <SFuld@alumni.cmu.edu.invalid> - 2011-05-18 23:27 -0700
                Re: Computer arithmetic problems worth exploring Quadibloc <jsavard@ecn.ab.ca> - 2011-05-19 15:19 -0700
                Re: Computer arithmetic problems worth exploring Stephen Fuld <SFuld@alumni.cmu.edu.invalid> - 2011-05-20 07:33 -0700
                Re: Computer arithmetic problems worth exploring Michael S <already5chosen@yahoo.com> - 2011-05-16 03:14 -0700
                Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-16 10:43 +0100
                Re: Computer arithmetic problems worth exploring Michael S <already5chosen@yahoo.com> - 2011-05-16 04:58 -0700
                Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-16 12:40 +0100
                Re: Computer arithmetic problems worth exploring MitchAlsup <MitchAlsup@aol.com> - 2011-05-15 10:12 -0700
                Re: Computer arithmetic problems worth exploring "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-05-14 13:22 -0700
                Re: Computer arithmetic problems worth exploring nmm1@cam.ac.uk - 2011-05-15 09:02 +0100
                Re: Computer arithmetic problems worth exploring "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-05-14 14:02 -0700
          Re: Computer arithmetic problems worth exploring "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-05-12 20:18 -0700
      Re: Computer arithmetic problems worth exploring Robert Myers <rbmyersusa@gmail.com> - 2011-05-09 14:32 -0700
        Re: Computer arithmetic problems worth exploring "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-05-09 16:08 -0700

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