On 11/16/18 12:38 PM, Daniel Krügler wrote:
Am Fr., 16. Nov. 2018 um 18:13 Uhr schrieb Ed Smith-Rowland
<3dw...@verizon.net>:
Greetings,
This is late but I wanted to put it out there just to finish a thing.
It's fairly straightforward constexpr of operators and some simple
functions for std::complex.
The only thing that jumped out was the norm function. We had this:
struct _Norm_helper<true>
{
template<typename _Tp>
static inline _Tp _S_do_it(const complex<_Tp>& __z)
{
_Tp __res = std::abs(__z);
return __res * __res;
}
};
Since abs can't be made constexpr for complex since it involves sqrt (It
probably could but that's another story) I had to fall back to the x^2 +
y^2. I don't know who that will bother. This version should be faster
and I can't think of any useful trustworthy difference numerically
either in terms of accuracy of stability.
Barring any feedback on that I'll clean it up and maybe rename my tests
from constexpr_all_the_things.cc to more_constexpr.cc ;-)
It builds and tests cleanly on x86_64-linux.
Hmmh, according to the recent working draft the following complex
functions are *not* constexpr:
arg, proj
So, shouldn't their new C++20-constexpr specifiers be added
conditionally (In the sense of gcc extensions)?
- Daniel
I did not see that those were not constexpr. I guess arg needs atan2
and proj
I'll remove the constexpr on those and adjust everything.
Thank you.
Ed
