X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?p=ginac.git;a=blobdiff_plain;f=ginac%2Fbasic.cpp;h=cf69c42cd2263dcfb722790ff65a7e2bacd4d8f6;hp=43dbf3366cebc54fb98a7b1810a889b9e5c89f97;hb=2c2f86ef17534853bc9b5e9c03229c5b57862d98;hpb=fb38db2d3476bf411940606824ef976187bf58f2

diff --git a/ginac/basic.cpp b/ginac/basic.cpp
index 43dbf336..cf69c42c 100644
--- a/ginac/basic.cpp
+++ b/ginac/basic.cpp
@@ -302,11 +302,16 @@ ex basic::subs(const lst & ls, const lst & lr) const
  *  @see ex::diff */
 ex basic::diff(const symbol & s, unsigned nth) const
 {
-    // FIXME: Check if it is evaluated!
+    // trivial: zeroth derivative
     if (!nth)
         return ex(*this);
+    
+    // evaluate unevalueted *this before differentiating
+    if (!(flags & status_flags::evaluated))
+        return ex(*this).diff(s, nth);
+    
     ex ndiff = derivative(s);
-    while (!ndiff.is_zero() &&    // stop differentiating zeroes
+    while (!ndiff.is_zero() &&    // stop differentiating zeros
            nth>1) {
         ndiff = ndiff.diff(s);
         --nth;