Error encountered when compiling the program of Aubo manipulator. Eigen cannot be found

/opt/ros/melodic/include/moveit/robot_model/joint_model.h:47:10: fatal error: Eigen/Geometry: No such file or directory
#include <Eigen/Geometry>

Reason:
the location of eigin library is/usr/include/eigin3/eigen. The system cannot find this location. We need to link it manually

Solution:
manually create a soft link to the upper level directory

sudo ln -sf /usr/include eigen3/Eigen /usr/include/Eigen
sudo ln -sf /usr/include/eigen3/unsupported /usr/include/unsupported