diff --git a/src/DataTree.cc b/src/DataTree.cc
index afa5288017a6964b809186189a34b024de0d1052..4fb897fdb548754333060abec3a3a65b5737c1d0 100644
--- a/src/DataTree.cc
+++ b/src/DataTree.cc
@@ -862,46 +862,6 @@ DataTree::isBinaryOpUsedOnType(SymbolType type, BinaryOpcode opcode) const
   return false;
 }
 
-bool
-DataTree::isTrinaryOpUsed(TrinaryOpcode opcode) const
-{
-  for (const auto &it : trinary_op_node_map)
-    if (get<3>(it.first) == opcode)
-      return true;
-
-  return false;
-}
-
-bool
-DataTree::isExternalFunctionUsed(int symb_id) const
-{
-  for (const auto &it : external_function_node_map)
-    if (it.first.second == symb_id)
-      return true;
-
-  return false;
-}
-
-bool
-DataTree::isFirstDerivExternalFunctionUsed(int symb_id) const
-{
-  for (const auto &it : first_deriv_external_function_node_map)
-    if (get<2>(it.first) == symb_id)
-      return true;
-
-  return false;
-}
-
-bool
-DataTree::isSecondDerivExternalFunctionUsed(int symb_id) const
-{
-  for (const auto &it : second_deriv_external_function_node_map)
-    if (get<3>(it.first) == symb_id)
-      return true;
-
-  return false;
-}
-
 int
 DataTree::minLagForSymbol(int symb_id) const
 {
diff --git a/src/DataTree.hh b/src/DataTree.hh
index 11bd2278bbb331e48e609d4afe5c1f98408c6c64..0b6e6b007c01c0bd6c436c186693a321d8ca092e 100644
--- a/src/DataTree.hh
+++ b/src/DataTree.hh
@@ -275,14 +275,6 @@ public:
   bool isBinaryOpUsed(BinaryOpcode opcode) const;
   //! Checks if a given binary op is used somewhere in the data tree on an endogenous variable
   bool isBinaryOpUsedOnType(SymbolType type, BinaryOpcode opcode) const;
-  //! Checks if a given trinary op is used somewhere in the data tree
-  bool isTrinaryOpUsed(TrinaryOpcode opcode) const;
-  //! Checks if a given external function is used somewhere in the data tree
-  bool isExternalFunctionUsed(int symb_id) const;
-  //! Checks if a given first derivative external function is used somewhere in the data tree
-  bool isFirstDerivExternalFunctionUsed(int symb_id) const;
-  //! Checks if a given second derivative external function is used somewhere in the data tree
-  bool isSecondDerivExternalFunctionUsed(int symb_id) const;
   //! Returns the minimum lag (as a negative number) of the given symbol in the whole data tree (and not only in the equations !!)
   /*! Returns 0 if the symbol is not used */
   int minLagForSymbol(int symb_id) const;