as a function of如何理解？

Ea is the net afterload imposed to the LV at endejection. Ejecting LV SV into the central aorta increases arterial pressure primarily as a function of the rate of ejection, central aortic compliance, mean vascular impedance, and initial diastolic arterial pressure of for that beat. Eacan be defined as the capability of the arterial system to increase pressure when SV increases; Eais the slope of the line running from the LV end-diastolic volume (LVEDV) to the LV end-systolic pressure (LVESP) end-systolic volume point on the LV pressure/volume (PV) loop

Ea是射血末期左室受到的净后负荷。左室每搏量（SV）射入中心大动脉后，主要依靠射血频率、大动脉顺应性、平均血管阻力以及那一次心搏时初始舒张期动脉压力来增加动脉压。Ea可以定义为，当SV增加时，动脉系统增加压力的能力；Ea是收缩期末容积点在左室压力/容积(PV)环上从左室舒张末容积(LVEDV)到左室收缩期末压力(LVESP)的连成的斜线(图1)。

动脉弹性阻力(Ea)

as a function of如何理解？