include Eigen2/3 headers optionally, for greater flexibility

diff --git a/modules/core/include/opencv2/core/eigen.hpp b/modules/core/include/opencv2/core/eigen.hpp
index 91bcb20..31bbd43 100644 (file)
--- a/modules/core/include/opencv2/core/eigen.hpp
+++ b/modules/core/include/opencv2/core/eigen.hpp
@@ -46,7 +46,9 @@
 #ifdef __cplusplus
 
 #include "cxcore.h"
+#ifndef EIGEN_CORE_H
 #include <Eigen/Core>
+#endif
 
 namespace cv
 {