* added ../GCC_default.mk and ../CLANG_default.mk  into your repository
* missing objects in Makefile, see Makefile:18            [-1]
* benchmark_tests.cpp:214   
  double check_sum       // GH: initialize!
  
 * Some comprehensive documents on results would be good. 
 
 * benchmarks.cpp
   MatMat(): swao j and k loop    // should be faster
   minor remarks in pdf.
   
   
* make codecheck COMPILER=CLANG_ > codecheck_gh.out