Performance of the scattering matrix computed with the method described in Sect. 5. Top: average scattering matrix computed from 300 realisations. Middle: its standard deviation. Bottom: difference between the scattering matrix computed from our method and the true scattering matrix computed from simulated catalogues. Left column: scattering matrix computed for σ₀ = 0.02. Middle column: scattering matrix computed for σ₀ = 0.05. Right column: scattering matrix computed for γ₀ = 0.02.