GNU bug report logs - #75105
(cl-random -1.0e+INF)

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Pip Cet <pipcet <at> protonmail.com>
Subject: bug#75105: closed (Re: bug#75105: (cl-random -1.0e+INF))
Date: Fri, 20 Jun 2025 06:37:02 +0000

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Your bug report

#75105: (cl-random -1.0e+INF)

which was filed against the emacs package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to 75105 <at> debbugs.gnu.org.

-- 
75105: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=75105
GNU Bug Tracking System
Contact help-debbugs <at> gnu.org with problems

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From: Pip Cet <pipcet <at> protonmail.com>
To: Mattias Engdegård <mattias.engdegard <at> gmail.com>
Cc: Eli Zaretskii <eliz <at> gnu.org>, 75105-done <at> debbugs.gnu.org,
 Stefan Monnier <monnier <at> iro.umontreal.ca>,
 Stefan Kangas <stefankangas <at> gmail.com>
Subject: Re: bug#75105: (cl-random -1.0e+INF)
Date: Fri, 20 Jun 2025 06:36:12 +0000

Mattias Engdegård <mattias.engdegard <at> gmail.com> writes:

> 18 feb. 2025 kl. 14.05 skrev Pip Cet <pipcet <at> protonmail.com>:
>
>> Okay for master?
>
> Looks fine.

Took me a while, but I've applied this and I'm closing the bug.

Pip

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From: Pip Cet <pipcet <at> protonmail.com>
To: bug-gnu-emacs <at> gnu.org,
 Mattias Engdegård <mattiasengdegard <at> gmail.com>,
 Stefan Monnier <monnier <at> iro.umontreal.ca>
Subject: (cl-random -1.0e+INF)
Date: Wed, 25 Dec 2024 23:27:09 +0000

The current behavior of (cl-random -1.0e+INF) is to return NaN with a
probability of 1.1920928955078125e-07, and -1.0e+INF in the remaining
cases.

There are at least two reasonable things cl-random can return for a
negative argument.  cl-random implements both, returning a float with
negative sign or a nonnegative integer.

There are at least two reasonable things cl-random can do in response to
a zero argument.  cl-random implements three of them:

(cl-random 0.0) is 0.0
(cl-random -0.0) is -0.0
(cl-random 0) throws an error

While "(while (not (isnan (cl-random -1.0e+INF))))" is an interesting
benchmark, its behavior may be somewhat surprising.

As this behavior has been in place since at least 1993 (when the
function was called random*), users may rely on it, and only the
docstring should be changed.

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