From: Eli Zaretskii <eliz@gnu.org>
To: help-gnu-emacs@gnu.org
Subject: Re: What is 0.01 here not 0.01 here 0.009999999999999?
Date: Fri, 02 Apr 2021 17:02:41 +0300 [thread overview]
Message-ID: <837dlkg4xq.fsf@gnu.org> (raw)
In-Reply-To: <courier.0000000060671F59.00003B9F@stw1.rcdrun.com> (message from Jean Louis on Fri, 02 Apr 2021 16:42:42 +0300)
> Date: Fri, 02 Apr 2021 16:42:42 +0300
> From: Jean Louis <bugs@gnu.support>
>
> I would like to get a number increased for 0.01:
>
> (defun rcd-vc-increase-decimal-revision-number (nn.nn)
> (let* ((nn.nn (format "%s" nn.nn))
> (nn.nn (format "%.2f" (string-to-number nn.nn)))
> (nn.nn (string-to-number nn.nn)))
> (+ nn.nn 0.01)))
>
> But result is not what I want, as I want to get 10.13, though it is
> tiny loss:
>
> (rcd-vc-increase-decimal-revision-number "10.12") → 10.129999999999999
Welcome to floating-point computations. 0.01 doesn't have an exact
binary representation, which is why you get what you get.
Suggested reading:
https://www.itu.dk/~sestoft/bachelor/IEEE754_article.pdf
next prev parent reply other threads:[~2021-04-02 14:02 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-02 13:42 What is 0.01 here not 0.01 here 0.009999999999999? Jean Louis
2021-04-02 13:56 ` Stefan Monnier
2021-04-02 17:03 ` Jean Louis
2021-04-02 17:41 ` Teemu Likonen
2021-04-02 18:44 ` Jean Louis
2021-04-02 20:46 ` John Yates
2021-04-02 21:19 ` Jean Louis
2021-04-02 22:04 ` John Yates
2021-04-02 23:29 ` Jean Louis
2021-04-03 4:39 ` Arthur Miller
2021-04-03 5:36 ` Jean Louis
2021-04-03 3:56 ` Arthur Miller
2021-04-03 5:19 ` Jean Louis
2021-04-03 13:54 ` Stefan Monnier
2021-04-03 16:26 ` Packages for ELPA, emacs-libpq Jean Louis
2021-04-02 14:02 ` Eli Zaretskii [this message]
2021-04-02 17:07 ` What is 0.01 here not 0.01 here 0.009999999999999? Jean Louis
2021-04-03 4:49 ` Arthur Miller
2021-04-16 20:41 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-04-17 10:53 ` Jean Louis
2021-04-19 10:51 ` Eric S Fraga
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