Link: https://eigen.tuxfamily.org/dox-devel/modules.html
Eigen is an open-source C++ linear algebra library. It’s built with pure header files; his means you can only locate its header files, not binary files like .so or .a. When you use it, you only need to import Eigen’s header file; you don’t need to link the library file (because it doesn’t have any library files).