diff --git a/Solver/STensor33.h b/Solver/STensor33.h
index f43e03d551f5e8f228db96d479704978a22b1d0a..8fa083ec0c98eec66383319c655a42c0e4bf11f4 100644
--- a/Solver/STensor33.h
+++ b/Solver/STensor33.h
@@ -102,6 +102,9 @@ class STensor33 {
     return *this;
   }*/
   void print(const char *) const;
+
+  const double* data() const{return _val;}
+  double* data() {return _val;}
 };
 
 // tensor product
diff --git a/Solver/STensor43.h b/Solver/STensor43.h
index 2ccec282b67cc3a8aab6e199ef73e51c980ec336..2384d7f51735c58cd6efa65b13065553d7818c86 100644
--- a/Solver/STensor43.h
+++ b/Solver/STensor43.h
@@ -153,6 +153,8 @@ class STensor43 {
     return *this;
   }*/
   void print(const char *) const;
+  const double* data() const {return _val;}
+  double* data() {return _val;}
 };
 
 // tensor product