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Big-O Notation


Big-O notation, written O(x) and pronounced "big-O of x," uses one of the Landau symbols and is used to symbolically express the asymptotic behavior of a given function.

In particular, if n is an integer variable which tends to infinity and x is a continuous variable tending to a specified x_0 in R or to +infty or -infty, if phi(n) and phi(x) are positive functions, and if f(n) and f(x) are arbitrary functions, then it is said that f in O(phi) provided that |f|<=Aphi for some positive constant A, for all sufficiently large n, or for all x in a punctured neighborhood of x_0 in the finite case, or sufficiently large in the indicated direction in the infinite case.

For eventually nonnegative real-valued functions f and positive functions phi, big-O notation and big-omega notation satisfy

 f(n) in O(phi(n)) <==> phi(n) in Omega(f(n)).

Additionally, big-O notation is related to little-O notation in that f in o(phi) is stronger than and implies f in O(phi).


See also

Asymptotic, Asymptotic Notation, Big-Omega Notation, Big-Theta Notation, Landau Symbols, Little-O Notation, Little-Omega Notation

Portions of this entry contributed by Christopher Stover

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References

Hardy, G. H. and Wright, E. M. "Some Notations." §1.6 in An Introduction to the Theory of Numbers, 5th ed. Oxford, England: Clarendon Press, pp. 7-8, 1979.Numberphile. "Omicron (the Symbol) in Mathematics." Featuring T. Padilla. Dec. 9, 2021. https://www.youtube.com/watch?v=JXtfKMH6X44.

Referenced on Wolfram|Alpha

Big-O Notation

Cite this as:

Weisstein, Eric W., with contributions by Christopher Stover. "Big-O Notation." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/Big-ONotation.html

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