SIAM Journal on Scientific Computing SIAM Journal on Scientific Computing, 2021, Special Section: 2020 Copper Mountain Conference, 43 (5), pp.S117-S145. ⟨10.1137/20M1349503⟩ SIAM Journal on Scientific Computing, Society for Industrial and Applied Mathematics, 2021, Special Section: 2020 Copper Mountain Conference, 43 (5), pp.S117-S145. ⟨10.1137/20M1349503⟩ SIAM Journal on Scientific Computing, Society for Industrial and Applied Mathematics, In press, ⟨10.1137/20M1349503⟩