typename base::Field at(typename base::Coord x) { return scalar * func.at(x); }
typename base::Field at(typename base::Coord x) { return left.at(x) + right.at(x); }
typename base::Field at(typename base::Coord x) { return scalar * func.at(x); }
typename base::Field at(typename base::Coord x) { return left.at(x) + right.at(x); }