Comparison of the HIMF from this work with the prediction from cosmological hydrodynamic simulations. Top: Comparison with the SIMBA full feedback model at z ∼ 0.365 and IllustrisTNG at z = 0.5. We show the HIMF determined in this work when assuming a linear (yellow stars) and polynomial model (blue squares) for the M_HI − M_⋆ relation. The best-fitting Schechter functions are shown with dashed orange and dotted-dashed green lines, respectively. We also show the predictions from SIMBA-100 (dashed yellow), SIMBA-50 (solid blue), IllustrisTNG-300 (dashed pink), and IllustrisTNG-100 (dotted-dashed red). For comparison, we show the HIMF from ALFALFA at z ∼ 0 (dashed purple). Bottom: Comparison with the different variations of the SIMBA-50 simulations. Shown are the predictions from the full feedback run (dashed green), the noAGN run (dotted black), the noX run (dashed gray), the noJet run (cyan line), and the noFB run (dotted brown).