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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libquadmath/114140] different results for std::fmin/std::fmax
 and quadmath fminq/fmaxq if one argument=signaling_NaN
Date: Wed, 28 Feb 2024 01:06:39 +0000
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Message-ID: <bug-114140-4-KUSBo1iFFo@http.gcc.gnu.org/bugzilla/>
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114140

--- Comment #10 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to g.peterhoff from comment #7)
> I think there is a misunderstanding. The problem is that std::fmin/std::f=
max
> and quadmath fminq/fmaxq give different results when only *one* argument =
is
> signaling_NaN.
> The standard (https://en.cppreference.com/w/cpp/numeric/math/fmin +
> https://en.cppreference.com/w/cpp/numeric/math/fmax) says:
> * If one of the two arguments is NaN, the value of the other argument is
> returned
> * Only if both arguments are NaN, NaN is returned
>=20
> quadmath fminq/fmaxq also return NaN if only *one* argument is signaling_=
NaN.

The cppreference page is wrong.
See https://sourceware.org/bugzilla/show_bug.cgi?id=3D20947 for reference o=
n why.=