Big O notation

Big O notation states that f grows no faster than g up to a constant factor, for arguments large enough. It is used to describe upper bounds on asymptotic growth, especially for algorithm running times.

f(x) = O(g(x)) \text{ as } x \rightarrow \infty \iff \exists M>0, \; x_0 \in \mathbb{R} : |f(x)| \leq M\, g(x) \quad \forall x \geq x_0

What the symbols mean

the function being bounded
the comparison function
a positive constant bounding the ratio
a threshold beyond which the bound holds
the variable tending to infinity

About this formula

  • FieldMathematics
  • TopicAsymptotic analysis
  • LevelUniversity
  • Also calledLandau notation, Bachmann-Landau notation, asymptotic notation, Landau symbol, order of growth upper bound, O notation definition
  • SourceWikidata Q269878

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