field lh (Float epsilon, Float t, const test& v) {
#ifdef  NEUMANN
  return field (v.get_vf_space(), 0);
#else //  NEUMANN
  size_t d = v.get_vf_space().get_geo().dimension();
  size_t k = v.get_vf_space().degree();
  Float beta = (k+1)*(k+d)/d;
  return epsilon*integrate ("boundary", 
         beta*penalty()*g(epsilon,t)*v
       - g(epsilon,t)*dot(grad_h(v),normal()));
#endif //  NEUMANN
}
field gh (Float epsilon, Float t, const field& uh, const test& v) {
  return - integrate (dot(compose(f,uh),grad_h(v)))
         + integrate ("internal_sides",
             compose (phi, normal(), inner(uh), outer(uh))*jump(v))
         + integrate ("boundary",
             compose (phi, normal(), uh, g(epsilon,t))*v);
}
