thanks to the hard work of Szabolcs Nagy (nsz), identifying the best
(from correctness and license standpoint) implementations from freebsd
and openbsd and cleaning them up! musl should now fully support c99
float and long double math functions, and has near-complete complex
math support. tgmath should also work (fully on gcc-compatible
compilers, and mostly on any c99 compiler).
based largely on commit 0376d44a890fea261506f1fc63833e7a686dca19 from
nsz's libm git repo, with some additions (dummy versions of a few
missing long double complex functions, etc.) by me.
various cleanups still need to be made, including re-adding (if
they're correct) some asm functions that were dropped.
the previous version not only failed to work in c++, but also failed
to produce constant expressions, making the macros useless as
initializers for objects of static storage duration.
gcc 3.3 and later have builtins for these, which sadly seem to be the
most "portable" solution. the alternative definitions produce
exceptions (for NAN) and compiler warnings (for INFINITY) on newer
versions of gcc.
Rich Felker