Relative difference between the various predicted matter power spectra and the Halofit prediction at z = 0 for different cosmologies. Top-left panel: using the mean values of the ΛCDM parameters given by Planck 2018 (Planck Collaboration VI 2020). Top-right panel: differences when the ΛCDM parameters are drawn from a five-dimensional Gaussian distribution with the diagonal given by five times the 1σ uncertainty quoted by Planck TTTEEE+lowE+lensing+BAO 2018. Bottom-left panel: differences when also the constant dark energy equation of state is drawn from a Gaussian distribution with a dispersion of 0.3. Bottom-right panel: difference for evolving dark energy models where, alongside w₀, also w_a is Gaussian distributed with a dispersion of 1.0. In the bottom panelsw₀ and w_a (if present) are always chosen in such a way that w(z) <  − 1/3. The feature visible at k ≈ 0.005 h Mpc⁻¹ corresponds the scale at which the non-linear corrections are turned on in CAMB.