Matter power spectra from simulations carried out with different codes (different line styles) for a ACDM cosmology. The left panels show the spectra at redshift z = 1 whereas the right panels show the spectra at redshift z = 0.667. The bottom panels show the relative difference with respect to the simulation carried out with MG–Arepo, see text for a discussion. The Nyquist wavenumber of the particle initial data is k_Ny ≈ 6.4 h Mpc⁻¹.