From: Jay Belanger <jay.p.belanger@gmail.com>
To: 19025@debbugs.gnu.org
Subject: bug#19025: 24.4; precision error when adding two floats
Date: Tue, 11 Nov 2014 20:28:49 -0600 [thread overview]
Message-ID: <87mw7xtan2.fsf@gmail.com> (raw)
In-Reply-To: <87oasd6vl4.fsf@gmail.com> (Alexis's message of "Wed, 12 Nov 2014 12:38:12 +1100")
>> (message "%s" (+ 379.744 57.93))
>>
>> The above prints 437.67400000000004. Same if I use 57.930, but if I
>> use 57.931 (below) I get the correct answer 437.675.
>>
>> (message "%s" (+ 379.744 57.931))
>>
>> I was able to work around by using format:
>>
>> (message "%s" (format "%f" (+ 379.744 57.93)))
>>
>> which prints 437.674000.
>>
>> FYI, I can replicate the issue with Emacs 21.3.1.
>
> Isn't this an artifact of the nature of floating-point arithmetic, rather than
> an issue with Emacs per se?
Yes, although it probably wouldn't be a bad idea to point out this issue
in the Elisp documentation.
next prev parent reply other threads:[~2014-11-12 2:28 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-12 0:36 bug#19025: 24.4; precision error when adding two floats Kevin W. Currey
2014-11-12 1:38 ` Alexis
2014-11-12 2:28 ` Jay Belanger [this message]
2014-11-12 2:42 ` Alexis
2014-11-12 2:06 ` Stefan Monnier
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