PG PRAGMA

More formally, action is a mathematical functional which takes the trajectory (also called path or history) of the system as its argument and has a real number as its result. Generally, the action takes different values for different paths.<ref name="mcgraw1">Template:Cite encyclopedia</ref> Action has dimensions of energy × time or momentum × length, and its SI unit is joule-second (like the Planck constant h).<ref>Template:Cite encyclopedia</ref>