Measured surface differential rotation of EI Eri and its comparison to other stars. Left panel: average cross-correlation map for EI Eri. The correlation peaks (white circles) are fitted with a quadratic differential rotation law. The resulting fit (continuous line) indicates a solar-type differential rotation with a shear parameter α = 0.036 ± 0.007. Right panel: extended version of the surface shear coefficient versus rotational period plot from Kővári et al. (2017). Squares denote results from the cross-correlation technique, while circles show differential rotational coefficients from the sheared image method. White and gray symbols correspond to single and binary stars, respectively. Symbol size increases from dwarfs to subgiants to giants. EI Eri is represented by the blue square at P_rot ≈ 2 days. The Sun is plotted with a dotted circle. The dotted and dash-dotted lines denote the linear fits to the points corresponding to singles and binaries, respectively, with slopes of |α| ∝ (0.0049 ± 0.00001)P_rot and |α| ∝ (0.0014 ± 0.00003)P_rot.