From a648dc9e508fa7089650e7069996f6844a4c1a13 Mon Sep 17 00:00:00 2001
From: Houtan Bastani <houtan@dynare.org>
Date: Thu, 31 May 2018 19:23:07 +0200
Subject: [PATCH] clarify error message

---
 src/ExprNode.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/ExprNode.cc b/src/ExprNode.cc
index f3f11156..6491718a 100644
--- a/src/ExprNode.cc
+++ b/src/ExprNode.cc
@@ -3147,7 +3147,8 @@ UnaryOpNode::substituteDiff(DataTree &static_datatree, diff_table_t &diff_table,
           else
             {
               // We know that the supported unary ops have already been substituted
-              cerr << "you can only use the `diff` operator on variables and certain unary ops" << endl;
+              cerr << "ERROR: You can only use the `diff` operator on variables and certain unary ops."
+                   << "       Try passing the `transform_unary_ops` option on the dynare command line." << endl;
               exit(EXIT_FAILURE);
             }