[PATCH] math: Add more input to atanh accuracy tests

[Sunil Pandey]

Hi Paul,

I got an optimization patch for function _ZGVeN16v_atanhf_skx. As a result of
optimization, ulps for(input 0x1.f80094p-8)  jumped from ~1.4 to ~2.4 and none
of the existing glibc atanh input catches it.

Currently at glibc master I am getting the following result.

Test: atanh_vlen16 (0x1.f80094p-8)
Result: 0x1.f80322p-8

I also tried input 0x1.ec2dd8p-4 but it doesn't catch the optimization accuracy
error jump for the proposed patch.

Thanks,
Sunil


On Tue, Feb 15, 2022 at 11:43 PM Paul Zimmermann
<Paul.Zimmermann@inria.fr> wrote:
>
>        Dear Sunil,
>
> > +# the next value generates larger error bounds on x86_64 (binary32)
> > +atanh 0x1.f80094p-8
>
> I only find a error of 0.598 ulp, whereas the largest error for binary32
> is obtained for 0x1.ec2dd8p-4 (1.73 ulp). More precisely for x=0x1.f80094p-8
> glibc 2.35 returns 0x1.f8031ep-8 (x86_64, skylake). Do you get a different value?
> Maybe you used different CFLAGS than the default ones?
>
> Best regards,
> Paul