Re: BASIC is 50

From	greymausg@mail.com
Newsgroups	comp.misc
Subject	Re: BASIC is 50
Date	2014-05-08 10:15 +0000
Message-ID	<slrnlmm4e9.ub.greymausg@gmaus.org> (permalink)
References	(2 earlier) <ljr6f8$6mn$1@dont-email.me> <53616180$0$59815$c3e8da3$e074e489@news.astraweb.com> <gknav.371282$sa2.196137@fx33.am4> <bsuj7gFd631U1@mid.individual.net> <Xtpav.335997$5V5.276603@fx08.am4>

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On 2014-05-07, BartC <bc@freeuk.com> wrote:
>
>
> "Huge" <Huge@nowhere.much.invalid> wrote in message
> news:bsuj7gFd631U1@mid.individual.net...
>> On 2014-05-07, BartC <bc@freeuk.com> wrote:
>>> "Rich" <rich@example.com> wrote in message
>>> news:53616180$0$59815$c3e8da3$e074e489@news.astraweb.com...
>>>> Scott Alfter <scott@alfter.diespammersdie.us> wrote:
>>>
>>>> 99.7099999999999999436561815002733055735006928443908691406250000000000000
>>>>
>>>> This is why floating point can be dangerous, and why floating point
>>>> should _NEVER_ ever be used to compute monetary values:
>>>
>>> Why not? Because the result might be off by a quadrillionth of a cent?
>>>
>>> Use rounding properly and it can be made to work (unless you're dealing
>>> with
>>> very large amounts such as the US debt then it's a bit trickier to avoid
>>> errors starting to affect the cents).
>>
>> Pretty obvious you've never worked in finance or banking.
>
> I've written software that worked with currency. I used floating point. But
> not for banking. (In that particular application, it needed to work in two
> linked currencies. The conversion rate between them was such that one or the
> other would generally always be a fraction of a cent wrong, rounded to the 
> nearest cent.)
>
> The only issue that might arise (and I can't remember it happening in my
> code), is in rounding a value ending in 0.5 cents or very close, then you
> have to decide to round up or down. The result might however have to match
> the same calculation done elsewhere, where the rounding might be the other
> way because their floating point result is different. (But there are ways of
> getting consistent, portable floating point results too.)
>
> (In any case, typical 64-bit floating point can represent amounts up to
> nearly $100 trillion, expressed in whole cents.)
>

[why floating point should not be used in finance]
Those tiny amounts, added together, can be diverted, as in the salami
scam. Python has decimal.Decimal for that sort of thing

Thread

BASIC is 50 Gordon Henderson <gordon+usenet@drogon.net> - 2014-04-30 09:34 +0000
  Re: BASIC is 50 Ant <ant@zimage.comANT> - 2014-04-30 03:42 -0700
    Re: BASIC is 50 Bob Eager <news0002@eager.cx> - 2014-04-30 10:46 +0000
      Re: BASIC is 50 Gordon Henderson <gordon+usenet@drogon.net> - 2014-04-30 12:03 +0000
  Re: BASIC is 50 Rich <rich@example.com> - 2014-04-30 11:12 +0000
    Re: BASIC is 50 scott@alfter.diespammersdie.us (Scott Alfter) - 2014-04-30 15:56 +0000
      Re: BASIC is 50 Rich <rich@example.com> - 2014-04-30 20:41 +0000
        Re: BASIC is 50 Will Honea <whonea@whonea.net> - 2014-04-30 18:38 -0600
          Re: BASIC is 50 Rich <rich@example.com> - 2014-05-01 02:38 +0000
            Re: BASIC is 50 Will Honea <whonea@whonea.net> - 2014-04-30 22:50 -0600
      Re: BASIC is 50 Rich <rich@example.com> - 2014-04-30 20:48 +0000
        Re: BASIC is 50 Richard Kettlewell <rjk@greenend.org.uk> - 2014-05-02 09:27 +0100
          Re: BASIC is 50 Tim Streater <timstreater@greenbee.net> - 2014-05-02 09:50 +0100
        Re: BASIC is 50 "BartC" <bc@freeuk.com> - 2014-05-07 10:48 +0100
          Re: BASIC is 50 Tim Streater <timstreater@greenbee.net> - 2014-05-07 10:57 +0100
          Re: BASIC is 50 Huge <Huge@nowhere.much.invalid> - 2014-05-07 11:20 +0000
            Re: BASIC is 50 "BartC" <bc@freeuk.com> - 2014-05-07 13:14 +0100
              Re: BASIC is 50 Marko Rauhamaa <marko@pacujo.net> - 2014-05-07 16:05 +0300
                Re: BASIC is 50 Paul Sture <nospam@sture.ch> - 2014-05-08 18:06 +0200
                Re: BASIC is 50 Marko Rauhamaa <marko@pacujo.net> - 2014-05-08 20:17 +0300
              Re: BASIC is 50 "James Harris" <james.harris.1@gmail.com> - 2014-05-07 16:08 +0100
                Re: BASIC is 50 "BartC" <bc@freeuk.com> - 2014-05-07 18:38 +0100
                Re: BASIC is 50 "James Harris" <james.harris.1@gmail.com> - 2014-05-07 19:09 +0100
                Re: BASIC is 50 Huge <Huge@nowhere.much.invalid> - 2014-05-07 19:08 +0000
              Re: BASIC is 50 greymausg@mail.com - 2014-05-08 10:15 +0000
                Re: BASIC is 50 "BartC" <bc@freeuk.com> - 2014-05-08 11:38 +0100
              Re: BASIC is 50 Paul Sture <nospam@sture.ch> - 2014-05-08 17:55 +0200
          Re: BASIC is 50 Paul Sture <nospam@sture.ch> - 2014-05-08 17:44 +0200
          Re: BASIC is 50 Rich <rich@example.com> - 2014-05-12 12:39 +0000
            Re: BASIC is 50 Marko Rauhamaa <marko@pacujo.net> - 2014-05-12 16:06 +0300
            Re: BASIC is 50 Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-05-12 22:48 +0100
              Re: BASIC is 50 Rich <rich@example.com> - 2014-05-13 12:03 +0000
                Re: BASIC is 50 "BartC" <bc@freeuk.com> - 2014-05-13 13:23 +0100
                Re: BASIC is 50 Rich <rich@example.com> - 2014-05-13 16:22 +0000
                Re: BASIC is 50 "BartC" <bc@freeuk.com> - 2014-05-13 19:42 +0100
                Re: BASIC is 50 "BartC" <bc@freeuk.com> - 2014-05-13 19:49 +0100
                Re: BASIC is 50 Rich <rich@example.com> - 2014-05-14 01:09 +0000
                Re: BASIC is 50 "BartC" <bc@freeuk.com> - 2014-05-14 09:51 +0100
                Re: BASIC is 50 bde@besplex.bde.org (Bruce Evans) - 2014-05-14 10:36 +0000
                Re: BASIC is 50 "BartC" <bc@freeuk.com> - 2014-05-14 12:58 +0100
                Re: BASIC is 50 bde@besplex.bde.org (Bruce Evans) - 2014-05-14 16:13 +0000
                Re: BASIC is 50 "BartC" <bc@freeuk.com> - 2014-05-14 19:24 +0100
                Re: BASIC is 50 Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-05-13 15:50 +0100
    Re: BASIC is 50 Johny B Good <johnny-b-good@invalid.ntlworld.com> - 2014-05-01 02:50 +0100
    Re: BASIC is 50 David Hume <David.Hume@example.com> - 2014-05-01 09:06 +0100
      Re: BASIC is 50 Gordon Henderson <gordon+usenet@drogon.net> - 2014-05-01 09:56 +0000
      Re: BASIC is 50 Rich <rich@example.com> - 2014-05-01 10:25 +0000
        Re: BASIC is 50 Marko Rauhamaa <marko@pacujo.net> - 2014-05-01 16:43 +0300
          Re: BASIC is 50 Gordon Henderson <gordon+usenet@drogon.net> - 2014-05-01 18:03 +0000
          Re: BASIC is 50 Bob Eager <news0002@eager.cx> - 2014-05-01 21:35 +0000
        Re: BASIC is 50 Rob <monst.oorzudo@ntlworld.com> - 2014-05-01 22:41 +0100
          Re: BASIC is 50 David Hume <David.Hume@example.com> - 2014-05-02 09:26 +0100
            Re: BASIC is 50 Hils <hils@saynotospam.net> - 2014-05-02 10:46 +0100
            Re: BASIC is 50 Johny B Good <johnny-b-good@invalid.ntlworld.com> - 2014-05-02 23:11 +0100
  Re: BASIC is 50 Anssi Saari <as@sci.fi> - 2014-04-30 17:51 +0300
  Re: BASIC is 50 Peter Percival <peterxpercival@hotmail.com> - 2014-05-14 17:40 +0100

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