Re: bug - boost::math::ccmath::copysign not work

From: Proton (matt_at_[hidden])
Date: 2022-08-18 02:24:51

> On Aug 17, 2022, at 4:11 PM, Gero Peterhoff via Boost <boost_at_[hidden]> wrote:
>
> Hi,
> I just see that boost::math::ccmath::copysign doesn't work.
> https://godbolt.org/z/9af1ME9fT
>
> cu
> Gero
>
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Gero,

The typical implementation of copysign and signbit involve type-punning which is not allowed in constexpr contexts. An example can be found here: https://android.googlesource.com/platform/bionic.git/+/brillo-m7-dev/libm/signbit.c. Due to this limitation we do not provide support for signed zero or analyzing the sign of NAN.

Matt