Systematic variation of maximum amplification factor (MAF; for definition see Sect. 2.2) and the pitch angle of the resulting swing amplification, plotted as a function of disk scale-height (β) for different Toomre Q values for a one-fluid case are shown in the top panel and bottom panel, respectively. For a given Toomre Q value, the resulting MAF decreases steadily with the increase of disk thickness, whereas the pitch angle (γ) increases monotonically with the increase of disk thickness, thus implying the spiral features will be more tightly wound. The definition of pitch angle used here is different from the standard definition used in literature, for details see text. 90° − γ will yield the pitch angle according to the standard definition.