Be more careful before converting to indexed.

[ginac.git] / check / exam_clifford.cpp

diff --git a/check/exam_clifford.cpp b/check/exam_clifford.cpp
index f504cd0ece3c56f2908ee7f97a064ef975e1f489..9503f162a72a38ed31a0ae03af25ca02990078e9 100644 (file)
--- a/check/exam_clifford.cpp
+++ b/check/exam_clifford.cpp
@@ -504,7 +504,8 @@ static unsigned clifford_check7(const ex & G, const symbol & dim)
        result += check_equal(e, pow(scalar*(dim-2), 2).expand() * clifford_unit(mu, G));
 
        // canonicalize_clifford() checks, only for symmetric metrics
-       if (ex_to<symmetry>(ex_to<indexed>(ex_to<clifford>(clifford_unit(mu, G)).get_metric()).get_symmetry()).has_symmetry()) {
+       if (is_a<indexed>(ex_to<clifford>(clifford_unit(mu, G)).get_metric()) &&
+           ex_to<symmetry>(ex_to<indexed>(ex_to<clifford>(clifford_unit(mu, G)).get_metric()).get_symmetry()).has_symmetry()) {
                e = clifford_unit(mu, G) * clifford_unit(nu, G) + clifford_unit(nu, G) * clifford_unit(mu, G);
                result += check_equal(canonicalize_clifford(e), 2*dirac_ONE()*unit.get_metric(nu, mu));