third_party/eigen/doc/TopicCMakeGuide.dox

namespace Eigen {

/**

\page TopicCMakeGuide Using %Eigen in CMake Projects

%Eigen provides native CMake support which allows the library to be easily
used in CMake projects.

\note %CMake 3.0 (or later) is required to enable this functionality.

%Eigen exports a CMake target called `Eigen3::Eigen` which can be imported
using the `find_package` CMake command and used by calling
`target_link_libraries` as in the following example:
\code{.cmake}
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)
\endcode

The above code snippet must be placed in a file called `CMakeLists.txt` alongside
`example.cpp`. After running
\code{.sh}
$ cmake path-to-example-directory
\endcode
CMake will produce project files that generate an executable called `example`
which requires at least version 3.3 of %Eigen. Here, `path-to-example-directory`
is the path to the directory that contains both `CMakeLists.txt` and
`example.cpp`.

Do not forget to set the <a href="https://cmake.org/cmake/help/v3.7/variable/CMAKE_PREFIX_PATH.html">\c CMAKE_PREFIX_PATH </a> variable if Eigen is not installed in a default location or if you want to pick a specific version. For instance:
\code{.sh}
$ cmake path-to-example-directory -DCMAKE_PREFIX_PATH=$HOME/mypackages
\endcode
An alternative is to set the \c Eigen3_DIR cmake's variable to the respective path containing the \c Eigen3*.cmake files. For instance:
\code{.sh}
$ cmake path-to-example-directory -DEigen3_DIR=$HOME/mypackages/share/eigen3/cmake/
\endcode

If the `REQUIRED` option is omitted when locating %Eigen using
`find_package`, one can check whether the package was found as follows:
\code{.cmake}
find_package (Eigen3 3.3 NO_MODULE)

if (TARGET Eigen3::Eigen)
  # Use the imported target
endif (TARGET Eigen3::Eigen)
\endcode

*/

}