Re: implicit promotion

From	Pete Becker <pete@versatilecoding.com>
Organization	Roundhouse Consulting, Ltd.
Newsgroups	comp.lang.c++
Date	2011-05-30 09:23 -1000
Message-ID	<2011053009235252042-pete@versatilecodingcom> (permalink)
References	<irusp0$6pi$1@reader1.panix.com> <Xns9EF5E0E419D65myfirstnameosapriee@216.196.109.131>
Subject	Re: implicit promotion

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On 2011-05-30 09:06:28 -1000, Paavo Helde said:

> Juha Nieminen <nospam@thanks.invalid> wrote in
> news:4de3dfee$0$2848$7b1e8fa0@news.nbl.fi:
> 
>> Paavo Helde <myfirstname@osa.pri.ee> wrote:
>>> As far as I can see from 5/9, no, float-int are converted to
>>> float-float.
>> 
>> Isn't that bad? An int might not be representable as a float, even
>> though
>> it may be as a double. The result of the division may be representable
>> with a float even though the int might not.
>> 
> 
> An int is quite surely representable as a float, up to some precision.

Well, yes, up to some precision. But it's often the case that the 
largest value that can be represented as an int cannot be represented 
exactly as a float. 32-bit ints and 32-bit doubles, for example.

In any case, the problem here is one of my favorite rants: programmers 
aren't taught how floating-point math works, so they end up treating it 
as magic. Nobody's bothered by 3*(1/3) not being 1, but somehow there's 
a perception that there's something unsavory about 10*(1.0/10.0) not 
having to be 1, even though it's exactly the same issue.

-- 
  Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The 
Standard C++ Library Extensions: a Tutorial and Reference 
(www.petebecker.com/tr1book)

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implicit promotion Ruben Safir <ruben@mrbrklyn.com> - 2011-05-30 01:44 +0000
  Re: implicit promotion red floyd <no.spam.here@its.invalid> - 2011-05-29 20:35 -0700
    Re: implicit promotion ruben safir <ruben@mrbrklyn.com> - 2011-05-30 00:01 -0400
      Re: implicit promotion Ian Collins <ian-news@hotmail.com> - 2011-05-30 16:08 +1200
        Re: implicit promotion Paavo Helde <myfirstname@osa.pri.ee> - 2011-05-30 01:18 -0500
          Re: implicit promotion Juha Nieminen <nospam@thanks.invalid> - 2011-05-30 11:45 +0000
            Re: implicit promotion Öö Tiib <ootiib@hot.ee> - 2011-05-30 05:49 -0700
              Re: implicit promotion Pete Becker <pete@versatilecoding.com> - 2011-05-30 08:58 -1000
                Re: implicit promotion Öö Tiib <ootiib@hot.ee> - 2011-05-30 12:01 -0700
                Re: implicit promotion Öö Tiib <ootiib@hot.ee> - 2011-05-30 12:07 -0700
                Re: implicit promotion Pete Becker <pete@versatilecoding.com> - 2011-05-30 09:07 -1000
                Re: implicit promotion Öö Tiib <ootiib@hot.ee> - 2011-05-30 12:13 -0700
                Re: implicit promotion Pete Becker <pete@versatilecoding.com> - 2011-05-30 09:27 -1000
            Re: implicit promotion Paavo Helde <myfirstname@osa.pri.ee> - 2011-05-30 10:17 -0500
              Re: implicit promotion Juha Nieminen <nospam@thanks.invalid> - 2011-05-30 18:20 +0000
                Re: implicit promotion Paavo Helde <myfirstname@osa.pri.ee> - 2011-05-30 14:06 -0500
                Re: implicit promotion Pete Becker <pete@versatilecoding.com> - 2011-05-30 09:23 -1000
                Re: implicit promotion Pete Becker <pete@versatilecoding.com> - 2011-05-30 09:29 -1000
                Re: implicit promotion Ruben Safir <ruben@mrbrklyn.com> - 2011-05-31 01:24 +0000
                Re: implicit promotion Ian Collins <ian-news@hotmail.com> - 2011-05-31 13:30 +1200
                Re: implicit promotion ruben safir <ruben@mrbrklyn.com> - 2011-05-31 00:52 -0400
                Re: implicit promotion Pete Becker <pete@versatilecoding.com> - 2011-05-30 17:36 -1000
              Re: implicit promotion Öö Tiib <ootiib@hot.ee> - 2011-05-30 11:39 -0700
                Re: implicit promotion Pete Becker <pete@versatilecoding.com> - 2011-05-30 09:02 -1000

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