Calculator Accuracy

From	Gordon Henderson <gordon+usenet@drogon.net>
Newsgroups	comp.misc
Subject	Calculator Accuracy
Date	2014-05-08 07:00 +0000
Organization	A noiseless patient Spider
Message-ID	<lkfa27$661$1@dont-email.me> (permalink)

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The BASIC is 50 thread, having diverged into floating point issues has
reminded me of a standard test that wa applied in all the schools where
I lived to determine if a calculator would be suitable for school use.

Put calculator into degrees mode, enter 45, then push SIN, COS, TAN,
then the inverses - INV-TAN, INV-COS and INV-SIN - then subtract 45 and
see what the result is.

With that, you do expect some rounding, but a lot of calculators were
so far off the mark it was quite incredible.

No-longer having a desktop scientific calculator (that works), I've
just tried it with gcalctool under my Linux desktop and given up. It's
a bloody calculator for goodness sake, not something I want to TYPE at!!!

Doing it using my RTB BASIC (standard IEEE 64-bit doubles), I end up
with -3.606714927e-11.

Gordon

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Calculator Accuracy Gordon Henderson <gordon+usenet@drogon.net> - 2014-05-08 07:00 +0000
  Re: Calculator Accuracy David Hume <David.Hume@example.com> - 2014-05-08 08:39 +0100
  Re: Calculator Accuracy Andy Burns <usenet.feb2014@adslpipe.co.uk> - 2014-05-08 09:14 +0100
    Re: Calculator Accuracy Andy Burns <usenet.feb2014@adslpipe.co.uk> - 2014-05-12 19:02 +0100
  Re: Calculator Accuracy "BartC" <bc@freeuk.com> - 2014-05-08 09:43 +0100
    Re: Calculator Accuracy Tim Streater <timstreater@greenbee.net> - 2014-05-08 09:53 +0100
      Re: Calculator Accuracy "BartC" <bc@freeuk.com> - 2014-05-08 10:22 +0100
        Re: Calculator Accuracy David Hume <David.Hume@example.com> - 2014-05-08 12:17 +0100
          Re: Calculator Accuracy RS Wood <rsw@therandymon.com> - 2014-05-08 14:09 +0000
            Re: Calculator Accuracy David Hume <David.Hume@example.com> - 2014-05-08 16:04 +0100
            Re: Calculator Accuracy Rich <rich@example.com> - 2014-05-08 16:49 +0000
              Re: Calculator Accuracy Rich <rich@example.com> - 2014-05-09 00:03 +0000
            Re: Calculator Accuracy Rich <rich@example.com> - 2014-05-09 00:10 +0000
              Re: Calculator Accuracy RS Wood <rsw@therandymon.com> - 2014-05-09 21:32 +0000
                Re: Calculator Accuracy Rich <rich@example.com> - 2014-05-10 03:30 +0000
            Re: Calculator Accuracy "G. Paul Ziemba" <paul+usenet@w6yx.stanford.edu> - 2014-05-09 03:43 +0000
    Re: Calculator Accuracy David Hume <David.Hume@example.com> - 2014-05-08 10:55 +0100
      Re: Calculator Accuracy "BartC" <bc@freeuk.com> - 2014-05-08 11:23 +0100
      Re: Calculator Accuracy Hils <hils@saynotospam.net> - 2014-05-08 12:09 +0100
        Re: Calculator Accuracy Hils <hils@saynotospam.net> - 2014-05-08 23:02 +0100
          Re: Calculator Accuracy Marc Auslander <marcslists@gmail.NOSPAM.com> - 2014-05-08 19:51 -0400
            Re: Calculator Accuracy Will Honea <whonea@whonea.net> - 2014-05-08 18:19 -0600
        Re: Calculator Accuracy Eric Pozharski <whynot@pozharski.name> - 2014-05-09 15:19 +0300
          Re: Calculator Accuracy David Hume <David.Hume@example.com> - 2014-05-09 19:06 +0100
            Re: Calculator Accuracy Eric Pozharski <whynot@pozharski.name> - 2014-05-10 08:38 +0300
              Re: Calculator Accuracy Eric Pozharski <whynot@pozharski.name> - 2014-05-12 09:30 +0300
          Re: Calculator Accuracy David Hume <David.Hume@example.com> - 2014-05-10 00:00 +0100
      Re: Calculator Accuracy Rich <rich@example.com> - 2014-05-08 11:40 +0000
  Re: Calculator Accuracy Rich <rich@example.com> - 2014-05-08 11:32 +0000
  Re: Calculator Accuracy Anssi Saari <as@sci.fi> - 2014-05-08 20:20 +0300
    Re: Calculator Accuracy Gordon Henderson <gordon+usenet@drogon.net> - 2014-05-08 17:40 +0000
      Re: Calculator Accuracy David Hume <David.Hume@example.com> - 2014-05-09 08:43 +0100
        Re: Calculator Accuracy Rich <rich@example.com> - 2014-05-09 10:42 +0000
        Re: Calculator Accuracy Whiskers <catwheezel@operamail.com> - 2014-05-09 21:56 +0100
      Re: Calculator Accuracy Geoff Clare <geoff@clare.See-My-Signature.invalid> - 2014-05-12 13:50 +0100
  Re: Calculator Accuracy Caecilius <nospam@spamless.invalid> - 2014-05-08 19:34 +0100
  Re: Calculator Accuracy Caecilius <nospam@spamless.invalid> - 2014-05-08 19:38 +0100
    Re: Calculator Accuracy Hils <hils@saynotospam.net> - 2014-05-08 22:06 +0100
  Re: Calculator Accuracy Paul Sture <nospam@sture.ch> - 2014-05-10 21:24 +0200
  Re: Calculator Accuracy Lewis <g.kreme@gmail.com.dontsendmecopies> - 2014-05-11 16:22 +0000
    Re: Calculator Accuracy Will Honea <whonea@whonea.net> - 2014-05-11 15:41 -0600
      Re: Calculator Accuracy Tim Streater <timstreater@greenbee.net> - 2014-05-11 23:02 +0100
  Re: Calculator Accuracy David Harmon <source@netcom.com> - 2014-05-12 18:20 -0700
  Re: Calculator Accuracy Yeechang Lee <ylee@pobox.com> - 2014-07-25 20:26 -0700

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