https://www.netlib.org/fdlibm/ https://www.netlib.org/fdlibm/readme
NOTE: “In this release, only double precision is supported.
"
https://www.netlib.org/cephes/
https://svnweb.freebsd.org/base/release/9.3.0/lib/msun/src/
https://core-math.gitlabpages.inria.fr/