An add-drop ring's through and drop spectra, 81 wavelengths from 1.548 to 1.556 µm, made by Bogaerts et al.'s Eqs. 5 and 6, exact: no grid
  made with κ₁² = 0.08, κ₂² = 0.05, 20 dB/cm, R = 10 µm; both fits from κ₁² = 0.12, κ₂² = 0.03, 10 dB/cm, R = 10.002 µm, to F below 1e-18
  L-BFGS-B with the adjoint gradient: 79 evaluations, each 81 circuit solves and 81 adjoint solves
  L-BFGS-B: κ₁²                          0.080000   paper 0.08       ± 1e-8      ok
  L-BFGS-B: κ₂²                          0.050000   paper 0.05       ± 1e-8      ok
  L-BFGS-B: loss (dB/cm)                20.000000   paper 20         ± 1e-5      ok
  L-BFGS-B: radius (µm)                 10.000000   paper 10         ± 1e-9      ok
  CMA-ES (seed 1), the response alone: 1504 evaluations, each 81 circuit solves
  CMA-ES: κ₁²                            0.080000   paper 0.08       ± 1e-8      ok
  CMA-ES: κ₂²                            0.050000   paper 0.05       ± 1e-8      ok
  CMA-ES: loss (dB/cm)                  20.000000   paper 20         ± 1e-5      ok
  CMA-ES: radius (µm)                   10.000000   paper 10         ± 1e-9      ok
  CMA-ES took 19 times as many evaluations
all 8 within tolerance of the paper
