Do you support C++ in 3.0.1.1 MATHLIB C66x?

We compiler folks are not responsible for that library.  That library is almost certainly implemented in C, and not C++.  Nonetheless, you can call functions in that library from C++ code.  The header files that come with the library should be able to handle that scenario.  Details are described here.  If the library cannot handle calls from C++, then that is a reasonable request to make.

Thanks and regards,

-George