Illustration of the starshade and pupil plane sampling (not to scale). The pupil radius is approximately ﹩\frac{1}{10}﹩ the starshade radius. The starshade grid is of size N_s · N_s with sampling Δs. The zero-padding of the starshade N_s · γ_ss necessary to achieve a ΔP sampling in the telescope plane with an FFT computation is illustrated. In the telescope plane, the telescope aperture of size N_P · N_P is shown, as is the slightly larger computed field of size ﹩{N}_{P}^{\parallel }\cdot {N}_{P}^{\parallel }﹩.