Let
be the Laplace transform of a function
. The final value theorem states,
under its stability conditions, that
A sufficient condition is that every pole of
lie in the open left half-plane, except possibly for a simple pole at
. The pole condition is essential:
the right-hand limit may exist even when
oscillates and has no final value.
For a sequence
with Z-transform
, the corresponding discrete form is
with the analogous requirement that the poles of lie inside the unit circle.