Eigen: environment setup 安装与配置

# Installation ## Install Eigen from source code ```sh git clone https://gitlab.com/libeigen/eigen.git ``` In fact, the header files in the `Eigen` subdirectory are the only files required to compile programs using Eigen. The header files are the same for all platforms. - Install using Cmake ```sh mkdir build cd build cmake .. -DCMAKE_INSTALL_PREFIX=myprefix make make install make doc ``` Eigen有用的只是些头文件，由于我一般使用Cmake来搭建自己的工程，所以我还是选择用Cmake编译安装。 这个源码工程本身就是最好的学习资料，推荐使用原码，用原码调试会更方便。 make option: ```sh ---------+-------------------------------------------------------------- Target | Description ---------+-------------------------------------------------------------- install | Install Eigen. Headers will be installed to: | / | Using the following values: | CMAKE_INSTALL_PREFIX: /home/yubao/data/software/eigen | INCLUDE_INSTALL_DIR: include/eigen3 | Change the install location of Eigen headers using: | cmake . -DCMAKE_INSTALL_PREFIX=yourprefix | Or: | cmake . -DINCLUDE_INSTALL_DIR=yourdir doc | Generate the API documentation, requires Doxygen & LaTeX check | Build and run the unit-tests. Read this page: | http://eigen.tuxfamily.org/index.php?title=Tests blas | Build BLAS library (not the same thing as Eigen) uninstall| Remove files installed by the install target ---------+-------------------------------------------------------------- ``` ## Install Eigen use repo ```sh sudo apt install libeigen3-dev ``` Where the Eigen is installed: ```sh sudo updatedb locate eigen3 ``` The default directory is ``/usr/include/eigen3/`` ## How to use Eigen in Cmake Project - Set Eigen3_DIR 如果是使用自己安装的版本的话，需要让Eigen3_DIR指向cmake目录。 Eg. ```sh export Eigen3_DIR=/home/yubao/data/software/eigen/share/eigen3/cmake ``` - CMakeLists.txt ```sh cmake_minimum_required (VERSION 3.0) project (myproject) find_package (Eigen3 3.3 REQUIRED NO_MODULE) add_executable (example example.cpp) target_link_libraries (example Eigen3::Eigen) ``` ## How to compile Eigen program without Cmake ```sh g++ -I /path/to/eigen/ my_program.cpp -o my_program ``` ## A simple first program ```sh #include #include using Eigen::MatrixXd; int main() { MatrixXd m(2,2); m(0,0) = 3; m(1,0) = 2.5; m(0,1) = -1; m(1,1) = m(1,0) + m(0,1); std::cout << m << std::endl; } ``` Result: ```sh 3 -1 2.5 1.5 ``` # Possible Errors ## Eigen/Core: No such file or directory ```sh [ 25%] Building CXX object CMakeFiles/useSophus.dir/useSophus.cpp.o /home/yubao/data/project/slambook2/useSophus/useSophus.cpp:3:10: fatal error: Eigen/Core: No such file or directory #include ^~~~~~~~~~~~ compilation terminated. CMakeFiles/useSophus.dir/build.make:62: recipe for target 'CMakeFiles/useSophus.dir/useSophus.cpp.o' failed make[2]: *** [CMakeFiles/useSophus.dir/useSophus.cpp.o] Error 1 CMakeFiles/Makefile2:67: recipe for target 'CMakeFiles/useSophus.dir/all' failed make[1]: *** [CMakeFiles/useSophus.dir/all] Error 2 Makefile:83: recipe for target 'all' failed make: *** [all] Error 2 ➜ build git:(master) ✗ ``` Solution: ```cpp #include ``` Refer: - https://github.com/wjakob/nanogui/issues/356 - ·[fatal error: Eigen/Core: No such file or directory #14868](https://github.com/opencv/opencv/issues/14868) # References - [Eigen-Getting started](http://eigen.tuxfamily.org/dox-3.2/GettingStarted.html#title0) - [Eigen-wiki](http://eigen.tuxfamily.org/index.php?title=Main_Page)