Pull math functions from the global namespace only when compiling cuda code with nvcc. When compiling with clang, we want to use the std namespace.
Pull math functions from the global namespace only when compiling cuda code with nvcc. When compiling with clang, we want to use the std namespace.

pthulhu/eigen,pthulhu/eigen,pthulhu/eigen,pthulhu/eigen,pthulhu/eigen