Riemann Sum
Let a closed interval
be partitioned
by points
,
where the lengths of the resulting intervals between the points are denoted
,
, ...,
. Let
be an arbitrary
point in the
th subinterval. Then the quantity
is called a Riemann sum for a given function
and partition,
and the value
is called the mesh
size of the partition.
If the limit of the Riemann sums exists as
,
this limit is known as the Riemann integral of
over the interval
. The shaded areas in the above plots show the
lower and upper sums for
a constant mesh size.
integral




