- sage: J1 = ComplexHermitianEJA(2)
- sage: J2 = TrivialEJA()
- sage: J = cartesian_product([J1,J2])
- sage: x = J.from_vector(vector(QQ, [-1, -1/2, -1/2, -1/2]))
- sage: x.is_invertible()
- True
- sage: x.det()
- 0
+6. Add special det/trace method overrides for the algebras where we
+ know them? The only reason this might be tricky is because the
+ obvious solution is to subclass EJAElement, but then we might
+ collide with e.g. the Cartesian product element subclass.