Unable to find Eigen3 with CMake

Question

I am kind of desperate: For my studies I need to work with Eigen and CMake. I\'m able to use Eigen if I copy the whole library in the directories where my compiler looks by

Answer 1

Turning my comment into an answer

The find package scripts - like FindEigen3.cmake - normally use the find_path() command to detect the package's include directory (see it's documentation for the full details).

FindEigen3.cmake uses the following code snippet:

find_path(EIGEN3_INCLUDE_DIR NAMES signature_of_eigen3_matrix_library
    PATHS
    ${CMAKE_INSTALL_PREFIX}/include
    ${KDE4_INCLUDE_DIR}
    PATH_SUFFIXES eigen3 eigen
)

So it looks in CMAKE_INSTALL_PREFIX which on Unix/Linux hosts is /usr/local by default.

The following has worked for me:

• Go to the Eigen source directory and run the CMake and installation steps

  > mkdir build
  > cd build
  > cmake ..
  > make install
  

• Then copy - as you have done - FindEigen3.cmake to your projects source directory.

• Now your code does find Eigen (just changed to list(APPEND ...))

  list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}")
  find_package(Eigen3 REQUIRED)
  

References

• Eigen & CMake
• CMake: Of what use is find_package() if you need to specify CMAKE_MODULE_PATH anyway?
• Cmake doesn't find Boost

Answer 2

Add the path of FindEigen3.cmake before find_package(Eigen3 REQUIRED), like this:

LIST(APPEND CMAKE_MODULE_PATH "/usr/share/cmake-2.8/Modules/")
find_package(Eigen3)