- if (ec[i].first[j] != 0)
- tv.push_back(power(vars[j], ec[i].first[j]));
+ const exp_vector_t& exp_vector(ec[i].first);
+
+ bug_on(exp_vector.size() != vars.size(),
+ "expected " << vars.size() << " variables, "
+ "expression has " << exp_vector.size() << " instead");
+
+ if (exp_vector[j] != 0)
+ tv.push_back(power(vars[j], exp_vector[j]));