diff --git a/Solver/function.h b/Solver/function.h
index 53c528d33a40bac21e19e16d3818920c5df4a064..1b9fadb8818429e83e61c010b0edd5c189526d83 100644
--- a/Solver/function.h
+++ b/Solver/function.h
@@ -87,6 +87,9 @@ public :
   inline bool somethingDependOnMe() {
     return !_dependOnMe.empty();
   }
+  inline bool doIDependOn(dataCacheDouble &other) {
+    return (_iDependOn.find(&other)!=_iDependOn.end());
+  }
   std::vector<dataCacheDouble*> _dependencies;
   std::vector<const fullMatrix<double>*> _depM;