Volunteering/Consulting for libm Development in glibc

[Joseph Myers]

On Mon, 17 Feb 2025, Adhemerval Zanella Netto wrote:

>   * Finish c23 support, which Joseph has started and he can fill the missing
>     spots.  The glibc still lack support for some functions (compoundn, pown,
>     powr, rootn, rsqrt).

Note that most of those are among the more complicated functions to 
implement because of the integer arguments (though I think they can all 
still be implemented in a type-generic way, so avoiding the need for five 
separate implementations for five separate formats including ldbl-128ibm, 
but such a type-generic implementation may not be very efficient).  Also I 
think Paul's testing of error bounds doesn't cover functions with integer 
arguments.

Adding support for _Float16, which I haven't started on yet, would also be 
a rather complicated change to ensure the support is completed everywhere 
in glibc (although there most functions, apart from a few such as fmaf16 
with double-rounding issues, can initially be implemented as wrappers for 
float functions then be changed incrementally to more efficient 
implementations).

FE_TONEARESTFROMZERO for RISC-V would also be quite complicated, again 
with changes in lots of places to ensure it's properly supported 
everywhere that currently has logic or tests to cover the different 
rounding modes.

-- 
Joseph S. Myers
josmyers@redhat.com