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Re: IE and IEE 754

Newsgroups comp.lang.javascript
Subject Re: IE and IEE 754
From "Evertjan." <exxjxw.hannivoort@inter.nl.net>
References <hN2dnbb1qJ8oT2DOnZ2dnUVZ_oGdnZ2d@westnet.com.au> <XnsA396E092544BEeejj99@194.109.133.133> <ltlfdh$tgs$1@solani.org>
Date 2014-08-28 00:07 +0200
Message-ID <XnsA397158B22A7eejj99@194.109.133.133> (permalink)

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"Christoph M. Becker" <cmbecker69@arcor.de> wrote on 27 aug 2014 in
comp.lang.javascript: 

>> Both are and must be wrong in the sense that the binary converions
>> of floting point fractional decimal values NEVER can be right.
> 
> Wrong.  Consider e.g. 0 or 2.

No 0 and 2 are integers.

>> So why use a standard that defines how wrong they must be?
> 
> To be able to quantify the inaccuracy.

There is no need for that.

>> Just remember every time,
>> that you should not compare such values without prior rounding.
> 
> AFAIK it is common to compare for equality with
> 
>     Math.abs(a - b) < epsilon

What has "common" to do with it?

It is a way, 
but a and b stay unrounded, 
and if reused and reused 
you might find yourself in trouble
with the wrong value of epsilon. 

> See also Number.EPSILON[1].

I don't see that.

> 
>> If you are a sticker for correctness and these are monitary values,
>> like $ or  , use integer cent values in variables, and write decimals
>> with string manupulation.
> 
> Are you suggesting that storing $123.45 as 12345 is better than storing
> it as 123.45?  

I am not 'suggesting' anything, 
I am not saying 'better',
just read my words.

But indeed, it is safer to manipulate integers.

> As ECMAScript implementations typically have no integer
> type, there is no difference regarding the precision of further
> calculations.

I wes not talking about the integer type, 
I was not talking about Javascript [ECMA if you like],
but about integers.

There is a rather a big difference 
'regarding the precision of further calculations.'
that difference is called safety of exactness.

Integers in binary storage are exact 
and so are simple arithmetic with those numbers, except for division, 
as long as the precision stays within practical limits.

input '23.45' string, store as a = 2345
input '23.4' string, store as b = 2340
do c = a - b
c contains 5
convert c to string d 0.05
write d

Compare this to:

document.write(23.45-23.4); // 0.05000000000000071

You are quite in your right 
not to call the first method "better",
but in monetary calculus, I would disagree.

-- 
Evertjan.
The Netherlands.
(Please change the x'es to dots in my emailaddress)

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IE and IEE 754 RobG <rgqld@iinet.net.au> - 2014-08-27 22:44 +1000
  Re: IE and IEEE 754 John Harris <niam@jghnorth.org.uk.invalid> - 2014-08-27 15:23 +0100
  IE and IEEE 754 (was: IE and IEE 754) Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-08-27 20:59 +0200
  Re: IE and IEE 754 "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-08-27 22:04 +0200
    Re: IE and IEE 754 "Christoph M. Becker" <cmbecker69@arcor.de> - 2014-08-27 22:35 +0200
      Re: IE and IEE 754 "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-08-28 00:07 +0200
        Re: IE and IEE 754 "Christoph M. Becker" <cmbecker69@arcor.de> - 2014-08-28 00:47 +0200
          Re: IE and IEE 754 Gene Wirchenko <genew@telus.net> - 2014-08-28 10:13 -0700
            Re: IE and IEE 754 "Christoph M. Becker" <cmbecker69@arcor.de> - 2014-08-28 22:15 +0200
              Re: IE and IEE 754 "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-08-28 23:24 +0200
                Re: IE and IEE 754 "Christoph M. Becker" <cmbecker69@arcor.de> - 2014-08-29 01:16 +0200
                Re: IE and IEE 754 "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-08-29 09:32 +0200
      Re: IE and IEE 754 Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-08-27 23:59 +0100
        Re: IE and IEE 754 "Christoph M. Becker" <cmbecker69@arcor.de> - 2014-08-28 02:55 +0200
          Re: IE and IEE 754 "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-08-28 09:50 +0200
            Re: IE and IEE 754 Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-08-28 12:21 +0200
              Re: IE and IEE 754 "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-08-28 13:42 +0200
          Re: IE and IEE 754 Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-08-28 11:27 +0100
            Re: IE and IEE 754 Gene Wirchenko <genew@telus.net> - 2014-08-28 10:16 -0700
              Re: IE and IEE 754 Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-08-29 00:04 +0100
                Re: IE and IEE 754 Gene Wirchenko <genew@telus.net> - 2014-08-29 11:15 -0700
                IEEE 754 (was: IE and IEE 754) "Christoph M. Becker" <cmbecker69@arcor.de> - 2014-08-29 21:30 +0200
                Re: IEEE 754 (was: IE and IEE 754) Gene Wirchenko <genew@telus.net> - 2014-09-02 11:22 -0700
                Re: IE and IEE 754 Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-08-29 20:42 +0100
                IEEE 754 (was: IE and IEE 754) "Christoph M. Becker" <cmbecker69@arcor.de> - 2014-08-29 23:29 +0200
                Re: IEEE 754 Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-08-29 23:27 +0100
                Re: IE and IEE 754 Dr J R Stockton <reply1400@merlyn.demon.co.uk.invalid> - 2014-08-30 20:32 +0100
                Re: IE and IEE 754 Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-08-31 01:04 +0100
                IE and IEEE 754 Dr J R Stockton <reply1400@merlyn.demon.co.uk.invalid> - 2014-09-01 23:05 +0100
    Re: IE and IEE 754 Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-08-28 00:05 +0100
      Re: IE and IEE 754 "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-08-28 08:56 +0200
        Re: IE and IEE 754 "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-08-28 09:51 +0200
          Re: IE and IEE 754 Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-08-28 11:16 +0100
            Re: IE and IEE 754 "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-08-28 13:34 +0200
              Re: IE and IEE 754 Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-08-28 23:41 +0100
                Re: IE and IEE 754 "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-08-29 09:09 +0200
                Re: IE and IEE 754 Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-08-29 12:39 +0100
                Re: IE and IEE 754 "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-08-29 16:55 +0200
                Re: IE and IEE 754 Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-08-29 18:28 +0100
                Re: IE and IEE 754 "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-08-30 00:37 +0200
                Re: IE and IEE 754 Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-08-29 23:53 +0100
                Re: IE and IEE 754 "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-08-30 01:08 +0200
                Re: IE and IEE 754 Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-08-30 00:40 +0100
                Re: IE and IEE 754 "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-08-30 09:32 +0200
                Re: IE and IEE 754 Gene Wirchenko <genew@telus.net> - 2014-08-29 11:22 -0700
                Re: IE and IEE 754 "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-08-30 00:14 +0200
  IE and IEEE 754 (was: IE and IEE 754) "Christoph M. Becker" <cmbecker69@arcor.de> - 2014-08-27 22:08 +0200
    Re: IE and IEEE 754 RobG <rgqld@iinet.net.au> - 2014-08-28 22:50 +1000
    Re: IE and IEEE 754 RobG <rgqld@iinet.net.au> - 2014-08-28 22:55 +1000
    Re: IE and IEEE 754 (was: IE and IEE 754) Dr J R Stockton <reply1400@merlyn.demon.co.uk.invalid> - 2014-08-28 21:50 +0100
      Re: IE and IEEE 754 (was: IE and IEE 754) "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-08-29 09:43 +0200
        Re: IE and IEEE 754 (was: IE and IEE 754) Denis McMahon <denismfmcmahon@gmail.com> - 2014-08-29 08:42 +0000
        Re: IE and IEEE 754 Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-08-30 16:24 +0200
          Re: IE and IEEE 754 "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-08-30 17:08 +0200
            Re: IE and IEEE 754 Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-08-30 18:12 +0200
              Re: IE and IEEE 754 "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-08-30 18:32 +0200

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