Fix bug in differentiation of a power.

[ginac.git] / ginac / ex.cpp

diff --git a/ginac/ex.cpp b/ginac/ex.cpp
index a5ede054b13eeb35ebb3b50fc90d4b3166a04a94..f1835377d2fbd9b6e0e83c289feea3c8361e36ef 100644 (file)
--- a/ginac/ex.cpp
+++ b/ginac/ex.cpp
@@ -240,6 +240,20 @@ ex ex::rhs() const
        return bp->op(1);
 }
 
+/** Check whether expression is a polynomial. */
+bool ex::is_polynomial(const ex & vars) const
+{
+       if (is_a<lst>(vars)) {
+               const lst & varlst = ex_to<lst>(vars);
+               for (lst::const_iterator i=varlst.begin(); i!=varlst.end(); ++i)
+                       if (!bp->is_polynomial(*i))
+                               return false;
+               return true;
+       }
+       else
+               return bp->is_polynomial(vars);
+}
+
 // private
 
 /** Make this ex writable (if more than one ex handle the same basic) by