The threshold in ldbl-96 atanhl for when to return the argument,
0x1p-28, is a bit too big, and that in ldbl-128ibm atanhl is much too
big (the relevant condition being x^3/3 being < 0.5ulp of x),
resulting in errors a bit above the limits of those considered
acceptable in glibc in the ldbl-96 case, and in large errors in the
ldbl-128ibm case. This patch changes those implementations to use
more appropriate thresholds and adds tests around the thresholds for
various formats.
Tested for x86_64, x86 and powerpc. x86_64 and x86 ulps updated
accordingly.
[BZ #18046]
[BZ #18047]
* sysdeps/ieee754/ldbl-128ibm/e_atanhl.c (__ieee754_atanhl): Use
0x1p-56L as threshold for just returning the argument.
* sysdeps/ieee754/ldbl-96/e_atanhl.c (__ieee754_atanhl): Use
0x1p-32L as threshold for just returning the argument.
* math/auto-libm-test-in: Add more tests of atanh.
* math/auto-libm-test-out: Regenerated.
* sysdeps/i386/fpu/libm-test-ulps: Update.
* sysdeps/x86_64/fpu/libm-test-ulp: Likewise.
