delta tensor makes itself square

diff --git a/ginac/tensor.cpp b/ginac/tensor.cpp
index f158ae65a7985b0359383565595b1bec05227ac8..1574bb66298e0acf49b2ce5ab9c874140dd59942 100644 (file)
--- a/ginac/tensor.cpp
+++ b/ginac/tensor.cpp
@@ -180,6 +180,13 @@ ex tensdelta::eval_indexed(const basic & i) const
        const idx & i1 = ex_to<idx>(i.op(1));
        const idx & i2 = ex_to<idx>(i.op(2));
 
+       // The dimension of the indices must be equal, otherwise we use the minimal
+       // dimension
+       if (!i1.get_dim().is_equal(i2.get_dim())) {
+               ex min_dim = i1.minimal_dim(i2);
+               return i.subs(lst(i1 == i1.replace_dim(min_dim), i2 == i2.replace_dim(min_dim)));
+       }
+
        // Trace of delta tensor is the (effective) dimension of the space
        if (is_dummy_pair(i1, i2)) {
                try {