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Re: sscanf question

From glen herrmannsfeldt <gah@ugcs.caltech.edu>
Newsgroups comp.lang.c
Subject Re: sscanf question
Date 2012-12-14 20:40 +0000
Organization Aioe.org NNTP Server
Message-ID <kag2rl$90p$1@speranza.aioe.org> (permalink)
References (7 earlier) <hfwys.1119952$Ol2.766606@fx25.am4> <kae67t$isr$1@speranza.aioe.org> <IpEys.510821$Wc4.18818@fx10.am4> <kaf5ge$ppe$1@speranza.aioe.org> <Z_Fys.966881$Rc7.497512@fx04.am4>

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BartC <bc@freeuk.com> wrote:

(snip, I wrote)
>>>> With floating point, the intermediate values might be rounded.

>>> Do you have a calculation where that rounding (which will be to the
>>> low-order bits of the representation) will actually give a different 
>>> result
>>> to doing the whole thing with integers? (And with ordinary amounts that 
>>> are
>>> likely to be encountered.)
 
>> With interest rates, it might be unusual, but, as previously mentioned,
>> exchange rates often go to four decimal places. It won't take such big
>> values to get rounding errors in that case. How long will it take you
>> to show that they don't occur?
 
> I'm asking you for *one* example where there might be a problem, 
> but you're asking me to verify zillions of possible calculations? 
> That's not fair!

When you put your money in a bank, you want to know that they will
do the interest computation right. You won't ask if they have an 
example where they did it wrong, but that they do it right under
all conditions.

Fortunately, you don't have to ask that because regulators will
ask for you.

-- glen

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Thread

sscanf question "Brian O'Brien" <bjobrien62@gmail.com> - 2012-12-12 13:29 -0800
  Re: sscanf question "BartC" <bc@freeuk.com> - 2012-12-12 21:43 +0000
  Re: sscanf question James Kuyper <jameskuyper@verizon.net> - 2012-12-12 16:52 -0500
  Re: sscanf question Les Cargill <lcargill99@comcast.com> - 2012-12-12 22:14 -0600
    Re: sscanf question Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-12-13 14:03 +0000
  Re: sscanf question falk@rahul.net (Edward A. Falk) - 2012-12-13 20:36 +0000
    Re: sscanf question Prathamesh Kulkarni <bilbotheelffriend@gmail.com> - 2012-12-13 13:40 -0800
      Re: sscanf question Fred K <fred.l.kleinschmidt@gmail.com> - 2012-12-13 14:31 -0800
        Re: sscanf question Fred K <fred.l.kleinschmidt@gmail.com> - 2012-12-13 14:33 -0800
          Re: sscanf question "BartC" <bc@freeuk.com> - 2012-12-13 22:51 +0000
            Re: sscanf question Keith Thompson <kst-u@mib.org> - 2012-12-13 15:45 -0800
              Re: sscanf question glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-14 00:06 +0000
              Re: sscanf question "BartC" <bc@freeuk.com> - 2012-12-14 02:33 +0000
                Re: sscanf question glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-14 03:25 +0000
                Re: sscanf question "BartC" <bc@freeuk.com> - 2012-12-14 11:50 +0000
                Re: sscanf question glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-14 12:19 +0000
                Re: sscanf question "BartC" <bc@freeuk.com> - 2012-12-14 13:38 +0000
                Re: sscanf question glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-14 20:40 +0000
                Re: sscanf question Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-12-16 03:34 -0800
          Re: sscanf question falk@rahul.net (Edward A. Falk) - 2012-12-15 03:28 +0000
            Re: sscanf question Les Cargill <lcargill99@comcast.com> - 2012-12-14 22:41 -0600
              Re: sscanf question Keith Thompson <kst-u@mib.org> - 2012-12-15 01:25 -0800
                Re: sscanf question glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-15 10:26 +0000
                Re: sscanf question Les Cargill <lcargill99@comcast.com> - 2012-12-15 13:24 -0600
                Re: sscanf question glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-15 20:15 +0000
                Re: sscanf question Les Cargill <lcargill99@comcast.com> - 2012-12-15 15:33 -0600
                [OT] Re: sscanf question Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-15 17:49 -0500
                Re: [OT] Re: sscanf question glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-16 00:16 +0000
            Re: sscanf question Barry Schwarz <schwarzb@dqel.com> - 2012-12-14 21:28 -0800
            Re: sscanf question glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-15 08:17 +0000
      Re: sscanf question Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-13 18:22 -0500
  Re: sscanf question "Brian O'Brien" <bjobrien62@gmail.com> - 2012-12-13 21:13 -0800
    Re: sscanf question Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-12-14 12:25 +0000

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