--- a/src/modules/bugs/functions/DSumFunc.h
+++ b/src/modules/bugs/functions/DSumFunc.h
@@ -21,6 +21,10 @@
 	std::vector<unsigned int> 
 	    dim(std::vector <std::vector<unsigned int> > const &dims) const;
 	bool isDiscreteValued(std::vector<bool> const &mask) const;
+	bool isLinear(std::vector<bool> const &mask, 
+		      std::vector<bool> const &fixed) const;
+	bool isScale(std::vector<bool> const &mask, 
+		     std::vector<bool> const &fixed) const;
     };
     
 }}