Histograms of the logarithm of the absolute value of the quotient of the spatial derivatives of the components of the electric current density from the MHD simulations and as obtained from the Stokes inversion. Top panel: ∂B_z/∂y (or alternatively ∂B_z/∂x). Middle panel: ∂B_x/∂y (or alternatively ∂B_y/∂x). Bottom panel: ∂B_y/∂z (or alternatively ∂B_x/∂z). The histograms correspond to the Stokes inversions described in Sect. 3: me (red), he1 (yellow), he2 (green), he3 (cyan), he4 (blue), and mhs (purple).