Definition: Letbe a subset of
and let
be a sequence of functions defined on
We say that
converges pointwise on
if
exists for each point
This means thatis a real number that depends only on
Ifis pointwise convergent then the function defined by
for everyis called the pointwise limit of the sequence
More formally, given anyand
there exists a natural number
depending only on
and
such that
for every
Definition Letbe a subset of
and let
be a sequence of real valued functions defined on
Then
converges uniformly to
if given any
there exists a natural number
such that
for every
depends only on
so uniform convergence implies pointwise convergence., but the converse is not true.
Example:
Asfor each
so
converges pointwise to zero.
Suppose now thatand
then
and
so
is not uniformly convergent.