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From: "g.peterhoff@t-online.de" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/77776] C++17 std::hypot implementation is poor
Date: Sat, 02 Mar 2024 15:52:01 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D77776

--- Comment #13 from g.peterhoff@t-online.de ---
Thanks for the suggestions:
template <typename _Tp>
constexpr _Tp __hypot3(_Tp __x, _Tp __y, _Tp __z)       noexcept
{
        if (std::isinf(__x) | std::isinf(__y) | std::isinf(__z))
[[__unlikely__]]
                return _Tp(INFINITY);
        __x =3D std::fabs(__x);
        __y =3D std::fabs(__y);
        __z =3D std::fabs(__z);
        const _Tp __max =3D std::fmax(std::fmax(__x, __y), __z);
        if (__max =3D=3D _Tp{}) [[__unlikely__]]
                return __max;
        __x /=3D __max;
        __y /=3D __max;
        __z /=3D __max;
        return std::sqrt(__x*__x + __y*__y + __z*__z) * __max;
}

The functions are then set to constexpr/noexcept.

regards
Gero=