Experiment with unknown solution from Section 8.5: Convergence of |$\eta_\ell(u_\ell)$| for |$\lambda = 10^{-5}$| and |$\theta\in\{0.2,\dots, 1\}$|⁠, where we compare naive initial guesses |$u_\ell^0 := 0$| (left) and nested iteration |$u_\ell^0 := u_{\ell-1}$| (right).