Top panel: comparison of SOAP forward model with respect ours, with, respectively, coloured lines marking the SOAP solutions and circles marking ours; parameters listed in Table 2 are used. The equatorial-on solution is presented in blue, an intermediate inclination of 45° is in orange, while the polar-on solution is presented in green. Fluxes have been normalised to the photospheric and unperturbed flux. An insert in the panel shows a comparison of the two models using different numbers of grid points to build the stellar surface. The insert follows the same notation of the main panel, but two profiles are added to mark the solution obtained using 500² grid points in the case of the SOAP code (dashed line) and ours (x marker). Bottom panel: residuals of two models evaluated as (F_SOAP − F_PAStar)/F_SOAP · 100, considering the lowest grid resolution.