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Date: Thu, 17 Aug 2023 17:57:12 +0200
From: Szabolcs Nagy <nsz@port70.net>
To: Paul Zimmermann <Paul.Zimmermann@inria.fr>
Cc: musl@lists.openwall.com
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	musl@lists.openwall.com
References: <p9u0bkf73vc2.fsf@coriandre.loria.fr>
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In-Reply-To: <p9u0bkf73vc2.fsf@coriandre.loria.fr>
Subject: Re: [musl] musl 1.2.4

* Paul Zimmermann <Paul.Zimmermann@inria.fr> [2023-08-16 16:39:25 +0200]:
> while updating our comparison of mathematical functions with Musl 1.2.4,
> I noticed the following two issues with acoshl and exp10l in double extended
> precision:
> 
> zimmerma@coriandre:~/svn/tbd/20/src/binary80$ VERBOSE=-v ./doit.musl acosh 1000
> Checking acosh with musl-1.2.4
> Using seed 2804715
> Using 6 threads
> NEW acosh 0 -1 -0x6.e2368c0ed74e5698p+16l [-nan] [inf] inf inf
> libm gives -0x4.b4d6a621e8e631f8p+0l
> mpfr gives nanl


yes it seems acoshl(x) does not handle x<0
(and can go wrong for x in [-2,-0x1p32])

> 
> zimmerma@coriandre:~/svn/tbd/20/src/binary80$ VERBOSE=-v ./doit.musl exp10 1000
> Checking exp10 with musl-1.2.4
> Using seed 2807610
> Using 6 threads
> exp10 0 -1 0x2.68826a13ef3fde64p+16376l [-nan] [inf] inf inf
> libm gives nanl
> mpfr gives infl

this seems to be a bug in powl: the reducl function can overflow.


thanks for the reports.