Upper panel: temporal evolution of the spin frequency of SGR 1745−2900. The solution given by Rea et al. (2013b) is plotted as a green solid line. The blue and magenta solid lines show solutions A and B of this work, respectively. The blue dashed lines are the extrapolation of solution A over the time span of solution B. The black line represents the fit over the whole time interval covered by observations (see text), while the vertical dashed lines refer to the times of the SGR-like short bursts detected by Swift/BAT (on 2013 April 25, June 7, and August 5). Central panel: phase residuals with respect to solution A (labelled as ϕ(t)_A), evaluated over the time validity interval MJD 56500.1–56594.1. Lower panel: phase residuals with respect to solution B (labelled as ν_B(t)), evaluated over the time validity interval MJD 56709.5–56929.