sums of indexed matrices are now possible

[ginac.git] / ginac / indexed.cpp

diff --git a/ginac/indexed.cpp b/ginac/indexed.cpp
index 4fa4256abfb286b86c95d427efa9a5c8de27c4c8..e23709d5f506647280eca2f54fb528f807a5dc8f 100644 (file)
--- a/ginac/indexed.cpp
+++ b/ginac/indexed.cpp
@@ -705,15 +705,17 @@ ex simplify_indexed(const ex & e, exvector & free_indices, const scalar_products
        // Simplification of sum = sum of simplifications, check consistency of
        // free indices in each term
        if (is_ex_exactly_of_type(e_expanded, add)) {
-               ex sum = _ex0();
+               ex sum = simplify_indexed(e_expanded.op(0), free_indices, sp);
 
-               for (unsigned i=0; i<e_expanded.nops(); i++) {
+               for (unsigned i=1; i<e_expanded.nops(); i++) {
                        exvector free_indices_of_term;
-                       sum += simplify_indexed(e_expanded.op(i), free_indices_of_term, sp);
-                       if (i == 0)
-                               free_indices = free_indices_of_term;
-                       else if (!indices_consistent(free_indices, free_indices_of_term))
+                       ex term = simplify_indexed(e_expanded.op(i), free_indices_of_term, sp);
+                       if (!indices_consistent(free_indices, free_indices_of_term))
                                throw (std::runtime_error("simplify_indexed: inconsistent indices in sum"));
+                       if (is_ex_of_type(sum, indexed) && is_ex_of_type(term, indexed))
+                               sum = sum.op(0).bp->add_indexed(sum, term);
+                       else
+                               sum += term;
                }
 
                return sum;