Hello,
On Thu, 3 Jul 2025, Yuao Ma wrote:
> This patch adds the required function for Fortran trigonometric functions to
> work with glibc versions prior to 2.26. It's based on glibc source commit
> 632d895f3e5d98162f77b9c3c1da4ec19968b671.
>
> I've built it successfully on my end. Documentation is also included.
>
> Please take a look when you have a moment.
+__float128
+cospiq (__float128 x)
+{
...
+ if (__builtin_islessequal (x, 0.25Q))
+ return cosq (M_PIq * x);
Isn't the whole raison d'etre for the trig-pi functions that the internal
argument reduction against multiples of pi becomes trivial and hence (a)
performant, and (b) doesn't introduce rounding artifacts? Expressing the
trig-pi functions in terms of their counterparts completely defeats this
purpose. The other way around would be more sensible for the cases where
it works, but the above doesn't seem very attractive.
Ciao,
Michael.
