L2hforadaptivity Ef F1 F3 F5

– Second derivative / curvature (super‑convergence recovery): f5 = h_K² * || ∇² u_h ||_L²(K) (or a patch‑recovered Hessian) Captures solution features that neither f1 nor f3 see alone (e.g., interior layers).

: This could stand for a variety of things depending on the context, such as a transformation (e.g., from L2 to H1 in Sobolev spaces in mathematics), a protocol, or a specific technique in a field like signal processing. l2hforadaptivity ef f1 f3 f5