Comparison between the 1D pulsation models, from Bessell et al. (1996), and the boundary conditions described in Sect. 2.1.1 and Appendix A, defined by Δφ_s and Δφ_p. The colours show the relative least-squares error (L2_rel), and the points indicates our calculated models and lines show Δφ_tot = Δφ_s + Δφ_p. Left and middle: model Z and model D from Bessell et al. (1996), which are fundamental mode pulsator models of o Ceti. Right: model E from Bessell et al. (1996), a first-overtone pulsator model of o Ceti.