Mention the CMAKE_PREFIX_PATH variable.

1 files changed, 7 insertions, 3 deletions

diff --git a/doc/TopicCMakeGuide.dox b/doc/TopicCMakeGuide.dox
index 896cfa831..cf767d0dd 100644
--- a/doc/TopicCMakeGuide.dox
+++ b/doc/TopicCMakeGuide.dox
@@ -32,9 +32,13 @@ 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`.
 
-If you have multiple installed version of %Eigen, you can pick your favorite one by setting the \c Eigen3_DIR cmake's variable to the respective path containing the \c Eigen3*.cmake files. For instance:
-\code
-cmake path-to-example-directory -DEigen3_DIR=$HOME/mypackages/share/eigen3/cmake/
+Do not forget to set the <a href="https://cmake.org/cmake/help/v3.7/variable/CMAKE_PREFIX_PATH.html">\c CMAKE_PREFIX_PATH </a> variable if Eigen is not installed in a default location or if you want to pick a specific version. For instance:
+\code{.sh}
+$ 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