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Final Value Theorem


Let F(s) be the Laplace transform of a function f(t). The final value theorem states, under its stability conditions, that

 lim_(t->infty)f(t)=lim_(s->0)sF(s).

A sufficient condition is that every pole of F(s) lie in the open left half-plane, except possibly for a simple pole at s=0. The pole condition is essential: the right-hand limit may exist even when f(t) oscillates and has no final value.

For a sequence x_n with Z-transform X(z), the corresponding discrete form is

 lim_(n->infty)x_n=lim_(z->1)(z-1)X(z),

with the analogous requirement that the poles of (z-1)X(z) lie inside the unit circle.


See also

Laplace Transform, Pole, Z-Transform

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References

Oppenheim, A. V.; Willsky, A. S.; and Nawab, S. H. Signals and Systems, 2nd ed. Upper Saddle River, NJ: Prentice Hall, 1997.

Cite this as:

Weisstein, Eric W. "Final Value Theorem." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/FinalValueTheorem.html

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