diff --git a/Solver/dofManager.h b/Solver/dofManager.h
index 9f85a86e9f454830d4ba97fccc50a4f75bdace4f..344930b6e2f97229aa47825b172d71236eeddbd4 100644
--- a/Solver/dofManager.h
+++ b/Solver/dofManager.h
@@ -547,6 +547,14 @@ class dofManager{
       R.push_back(it->first);
     }
   }
+
+  int getDofNumber(Dof& key){
+		std::map<Dof,int>::iterator it = unknown.find(key);
+		if (it == unknown.end()) {
+			return -1;
+		}
+		else return it->second;
+	};
 };
 
 template<class T>