Evolution of the TIgwIMF for a galaxy with the boxy SFH shown in Fig. 2, where ξ is the total number of stars within a unit mass range. The assumed lowest and highest possible stellar mass is 0.08 M_⊙ and 150 M_⊙, respectively, following Yan et al. (2017). The solid lines represent the TIgwIMF after 10, 20, ..., and 1000 Myr since the beginning of the star formation (from bottom to top). The colour of the lines indicates the metallicity [Z] (as defined in Eq. (5)) in gas at the time. The colour-coding is the same as in Figs. 3 and 4; the white dots in the colour bar indicate the available initial metallicity values of the stellar yield table (see Sect. 4.4) and the white line indicates the initial metallicity of the last stellar population (i.e. the most metal-rich population). The dashed line is the canonical IMF given by Kroupa (2001), normalized to have the same ξ as the final TIgwIMF at M_* = 1.