Notes > Computation and Algorithms > BigO Notation 
Algorithms can be associated with an equation which defines the number of steps the algorithm takes, typically in terms of "n" (e.g. n^{2}/2 + 3). To categorise algorithms into certain groups, BigO notation is used. The equation n^{2}/2 + 3 would mean that the algorithm associated with it is of order O(n^{2}).
BigO notation igonores any constant factors and any lower order factors of n. Take another example of n^{2} + n + 1 which would also be of order O(n^{2}). See Program Complexity for more information.
The following list gives some names and examples of the common orders used to describe functions. These orders are ranked from fast (top) to slow (bottom).
 Logarithmic  O(log n)
 Linear  O(n)
 Linearithmic  O(n log n)
 Quadratic  O(n^{2})
 Exponential / Geometric  O(c^{n})
Search for "BigO Notation" on:
Google 
Kelkoo 
Amazon 
eBay (UK) 
eBay (US)
Search for "BigO Notation" on the rest of Computing Students: BigO Notation
