Add header only library

[SuperKlever]

I downloaded the header only library (NumCpp) and now I have the /include directory. The library folder is located in the same directory as my .ipynb file.
I'm trying to add add library to include path, however it doesn't seem to work.

#pragma cling add_include_path("/NumCpplib/include")
#include "NumCpplib/include/NumCpp.hpp"

After running this code, I get the classic error that the path to the library was not found.

./NumCpplib/include/NumCpp/Coordinates.hpp:30:10: fatal error: 'NumCpp/Coordinates/Cartesian.hpp' file not found

What am I doing wrong?