So far we’ve been exploring exterior calculus purely in the smooth setting. Unfortunately this
theory was developed by some old-timers who did not know anything about computers, hence it
cannot be used directly by machines that store only a finite amount of information. For instance, if
we have a smooth vector field or a smooth 1-form we can’t possibly store the direction of every
little “arrow” at each point—there are far too many of them! Instead, we need to keep track of a
discrete (or really, finite) number of pieces of information that capture the essential behavior of the
objects we’re working with; we call this scheme discrete exterior calculus (or DEC for short). The big
secret about DEC is that it’s literally nothing more than the good-old fashioned (continuous) exterior
calculus we’ve been learning about, except that we integrate differential forms over elements of
our mesh.