use better methods

nifty4/domains/rg_space.py

@@ -133,7 +133,7 @@ class RGSpace(StructuredDomain):
             return np.sqrt(np.nonzero(tmp)[0])*self.distances[0]
         else:  # do it the hard way
             # FIXME: this needs to improve for MPI. Maybe unique()/gather()?
-            tmp = dobj.to_global_data(self.get_k_length_array().val)
+            tmp = self.get_k_length_array().to_global_data()
             tmp = np.unique(tmp)
             tol = 1e-12*tmp[-1]
             # remove all points that are closer than tol to their right