- mentioned "Derivative" function

diff --git a/NEWS b/NEWS
index 0489cb5b66b7aa5ba56633b3ba59c5f9a794d511..04f3e55989afc248f80462fe6bed88c346ec8532 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -16,6 +16,8 @@ This file records noteworthy changes.
 * ex::to_rational() provides a way to extend the domain of functions like
   gcd() and divide() that only work on polynomials or rational functions (the
   good old ex::subs() method reverses this process)
+* Calling diff() on a function that has no derivative defined returns the
+  inert derivative function "Derivative".
 * Several new timings in the check target.  Some of them may be rather rude 
   at your machine, feel free to interrupt them.