bits of libsunmath are in libm, privately, and seemingly unused
Parts, but not all, of libsunmath's extra functions are actually built and present in libm, but are scoped local to libm.
The ones I've looked at seem to be unused within libm, and not in libm for any obvious reason (except the weird history of libm/mopt/sunmath I assume).
These include exp10, exp2, log2 at least.
compound and annuity are not present, so it's not all sunmath things.
sinpi seems to be there, tanpi doesn't.
Basically, there's no obvious logic behind what is present and what is not. This seems to have also been true with libm as it was delivered from devpro.
We should, on a case-by-case basis:
Promote useful things to visible (this is especially a good idea if the math library on other systems provides them)
Remove things that are unused by libm, and unusable by others (since they're not externally visible)