The Poisson problem by the hybrid discontinuous Galerkin method – local averaging function
size_t k = uh.get_space().degree();
size_t d = uh.get_geo().dimension();
space Zh (uh.get_geo(),
"P0");
integrate_option iopt;
iopt.invert = true;
if (k >= 1) {
iopt.set_order(2*k+2);
}
const space& Mh = lambda_h.get_space();
}