First-order magnetic splitting for dipolar (l = 1, left top panel) and quadrupolar (l = 2, right top panel) mixed modes in the studied 1.5 M_⊙ red giant star. The dots correspond to the full expression for the splitting (Eqs. (B.1) and (B.2)) computed numerically using the GYRE and MESA codes, and the solid lines are the asymptotic solutions given in Eq. (20). The ζ function related to the mixed character of modes propagating in evolved low-mass stars is plotted as a dotted grey line. Finally, the vertical thick orange line indicates the position of ω_max = 2πν_max. Bottom panels: relative errors between the asymptotic magnetic splittings as derived in Eq. (20) and their full expression given in Appendix B for dipolar (left panel) and quadrupolar (right panel) modes, respectively.