500 x 220 nm strip of 3.473 in 1.444 at 1550 nm (Chrostowski & Hochberg, Fig. 3.14)
  the quarter of a 2.1 x 1.5 um window, zero walls; TE-like n_eff by scheme
  grid     nodes       standard scheme   Hadley's equations   TE fraction
  10 nm    106 x 76    2.445713          2.442212             0.973
  5 nm     211 x 151   2.444396          2.442178             0.972
  the standard scheme's grids: error 1.3e-3, not_converged at 1e-4 (its corners)
  TE-like n_eff, Hadley's, 5 nm          2.442178   paper 2.443      ± 3e-3      ok
  TE-like n_eff, Hadley's, its grids     2.442178   on 2 grids, error 3.4e-5 ≤ 1e-4 ok
all 2 within tolerance of the paper
