Write CmakeLists for Eigen

About

I wanted to try Eigen again after a long time, so I created a CMakeLists file and set up an environment to run it. Eigen is a C++ matrix operation library that operates very efficiently. It will be useful for various projects.

CmakeLists.txt

cmake_minimum_required(VERSION 3.14)

project(EigenExample)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

include(FetchContent)
FetchContent_Declare(
    CLI11
    GIT_REPOSITORY https://github.com/CLIUtils/CLI11.git
    GIT_TAG        v2.3.2
)
FetchContent_MakeAvailable(CLI11)

FetchContent_Declare(
    Eigen3
    GIT_REPOSITORY https://gitlab.com/libeigen/eigen.git
    GIT_TAG 3.4.0
)
FetchContent_MakeAvailable(Eigen3)


add_executable(EigenExample src/main.cpp)

target_link_libraries(EigenExample PRIVATE CLI11 Eigen3::Eigen)

Small Test on Eigen

#include <iostream>
#include <CLI/CLI.hpp>
#include <Eigen/Dense>


int main(int argc, char** argv){
    CLI::App app("Example CLI");
    double e11 = 1.0;
    double e12 = 2.0;
    double e21 = 3.0;
    double e22 = 4.0;
    app.add_option("-a,--element11", e11, "Set e11");
    app.add_option("-b,--element12", e12, "Set e12");
    app.add_option("-c,--element21", e21, "Set e21");
    app.add_option("-d,--element22", e22, "Set e22");

    CLI11_PARSE(app, argc, argv);

    Eigen::Matrix2d A;
    A << double(e12), double(e12),
         double(e21), double(e22);

    Eigen::Vector2d b(5, 6);

    Eigen::Vector2d x = A * b;

    std::cout << "A:\n" << A << "\n";
    std::cout << "b:\n" << b << "\n";
    std::cout << "A * b:\n" << x << "\n";

    Eigen::Matrix2d A_inv = A.inverse();
    std::cout << "A inverted:\n" << A_inv << "\n";

    return 0;
}

Build

cmake ..
cmake --build .

Built target CLI11
Consolidate compiler generated dependencies of target EigenExample
Building CXX object CMakeFiles/EigenExample.dir/src/main.cpp.o

Okay, seems that I stood at a point to start with it.