Index: kernel/include/IMP/Vector3D.h
===================================================================
--- kernel/include/IMP/Vector3D.h	(revision 528)
+++ kernel/include/IMP/Vector3D.h	(working copy)
@@ -58,6 +58,14 @@
     return scalar_product(o);
   }
 
+  //! product with scalar
+  Vector3D operator*(Float s) const {
+    return Vector3D(operator[](0)*s, 
+                    operator[](1)*s,
+                    operator[](2)*s); 
+                    
+  }
+
   //! \return the vector product of two vectors.
   /** \param[in] vec2 The other vector to use in the product.
    */
@@ -92,6 +100,13 @@
                     operator[](2)-o[2]);
   }
 
+  //! \return Sum of two vectors.
+  Vector3D operator+(const Vector3D &o) const {
+    return Vector3D(operator[](0)+o[0],
+                    operator[](1)+o[1],
+                    operator[](2)+o[2]);
+  }
+
   void show(std::ostream &out) const {
     out << "(" << operator[](0) << ", " << operator[](1) << ", "
         << operator[](2) << ")";
@@ -102,6 +117,15 @@
 
 IMP_OUTPUT_OPERATOR(Vector3D);
 
+
+//! product with scalar
+inline Vector3D operator*(Float s, const Vector3D &o) {
+  return Vector3D(o[0]*s, 
+                  o[1]*s,
+                  o[2]*s); 
+  
+}
+
 } // namespace IMP
 
 #endif  /* __IMP_VECTOR_3D_H */