(p.i*p.i).get_free_indices() returned (.i) instead of ()

diff --git a/ginac/indexed.cpp b/ginac/indexed.cpp
index d1d5f7287b07d01a723f22adf0e21c37ffdcb15d..ad17a497a9dc703e52cd435d6901312071beab42 100644 (file)
--- a/ginac/indexed.cpp
+++ b/ginac/indexed.cpp
@@ -499,10 +499,27 @@ exvector ncmul::get_free_indices() const
        return free_indices;
 }
 
+struct is_summation_idx : public std::unary_function<ex, bool> {
+       bool operator()(const ex & e)
+       {
+               return is_dummy_pair(e, e);
+       }
+};
+
 exvector power::get_free_indices() const
 {
-       // Return free indices of basis
-       return basis.get_free_indices();
+       // Get free indices of basis
+       exvector basis_indices = basis.get_free_indices();
+
+       if (exponent.info(info_flags::even)) {
+               // If the exponent is an even number, then any "free" index that
+               // forms a dummy pair with itself is actually a summation index
+               exvector really_free;
+               std::remove_copy_if(basis_indices.begin(), basis_indices.end(),
+                                   std::back_inserter(really_free), is_summation_idx());
+               return really_free;
+       } else
+               return basis_indices;
 }
 
 /** Rename dummy indices in an expression.