Acceleration profile of the jet in M 87. We plot the Lorentz factor measured from WISE analysis of VLBA images at 7 mm (blue), 2 cm (green), from Cheung et al. (2007) using VLBA at 1.7 GHz (red), from Giroletti et al. (2012) and Asada et al. (2014) using EVN at 1.7 GHz (magenta and gray respectively), and from optical images using HST (Biretta et al. 1999; orange). The Lorentz factor and de-projected z axis are computed assuming θ = 18° (z ~ 3.2 z_obs). Two regimes are found with a linear acceleration up to z ~ 10³R_s, followed by a slow acceleration up to HST-1