think it can be simplified quite a bit. The old code includes
<cmath> for pre-10.2 and anything using something other than g++ 4
and then uses std::isnan. For the most current version, it leaves
out cmath and uses isnan(). std::isnan and cmath work for the
current version, so I just made it include cmath if __APPLE__ is
defined and removed the ifdef between versions of OS X for isnan
related things.
This way the code is all the same, and it's not fragile to someone
including <cmath> prior to including osg/Math."
62edacece5