Add a simplification layer when reading derivatives

xpp_parser.pl

@@ -198,9 +198,11 @@ read_xpp_line(Line_raw, _Split, Id) :-
     atomic_list_concat(['d',Sub.1,'/dt = ',Sub.2], Line)
   ),
   !,
-  read_term_from_codes(Line, Expr, [variable_names(VariableNames), module(ode)]),
-  name_variables_and_anonymous(Expr, VariableNames),
-  add_ode(Id, Expr),
+  read_term_from_codes(Line, DX = Expr, [variable_names(VariableNames), module(ode)]),
+  name_variables_and_anonymous(DX = Expr, VariableNames),
+  distribute(Expr, Expanded),
+  simplify(Expanded, Clear_Expr),
+  add_ode(Id, DX = Clear_Expr),
   fail.
 
 read_xpp_line(Line, _Split, Id) :-