X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?p=ginac.git;a=blobdiff_plain;f=ginac%2Fsymbol.cpp;h=1a8ef59cd2a5d0d15f0cd6d2e147c631456b587d;hp=43927dc3a3192df4e2780440c9e701b7c3ec0066;hb=97af29c12bb3074cfb4e674d71000f0712c51ba2;hpb=cbc11c7f58c923953c54fcba798bf97e7deb81a3

diff --git a/ginac/symbol.cpp b/ginac/symbol.cpp
index 43927dc3..1a8ef59c 100644
--- a/ginac/symbol.cpp
+++ b/ginac/symbol.cpp
@@ -259,6 +259,19 @@ ex symbol::subs(const lst & ls, const lst & lr) const
 
 // protected
 
+/** Implementation of ex::diff() for single differentiation of a symbol.
+ *  It returns 1 or 0.
+ *
+ *  @see ex::diff */
+ex symbol::derivative(const symbol & s) const
+{
+    if (compare_same_type(s)) {
+        return _ex0();
+    } else {
+        return _ex1();
+    }
+}
+
 int symbol::compare_same_type(const basic & other) const
 {
     GINAC_ASSERT(is_of_type(other,symbol));