This answer is only a summary from the comments above:
At compile-time you have
EIGEN_WORLD_VERSION
,EIGEN_MAJOR_VERSION
andEIGEN_MINOR_VERSION
, you can easily embed this information in your application.3.1.91
sounds like abeta version
of3.2
.The version number macros are defined in
Macros.h
located at\Eigen\src\Core\util\
.