# Pronunciation of the big-O notation

How should I pronounce the following things? (These are complexities of algorithms.)

• O(n)
• O(n*log(n))
• O(n^2)
• This question is more appropriate for math.stackexchange.com or cstheory.stackexchange.com. Jun 1, 2011 at 16:28
• @Mitch cstheory is for research level questions only, see cstheory.stackexchange.com/faq Jun 2, 2011 at 18:25
• I think this is a pointless question. Does OP really want to know whether O is pronounced as Owe rather than Big Oh? Or maybe it should be pronounced zer-OWE? I'm voting to close, and if I could delete it I would do that. Jun 23, 2011 at 3:06

Pronunciation would be:

• order n
• order n log n
• order n squared
• If the context (of computational order) is already established, I've also heard "o of n" (etc). Jun 1, 2011 at 16:38
• Its just known as the 'Big O' in my discrete math class. aka the maximum amount of times an algorithm will be run. Jun 23, 2011 at 2:56

In the talks I've seen that involve algorithm complexity, I've heard it most often pronounced "oh of n", "oh of n log n", etc.

Mathematicians and CS theorists also use a lowercase o and a capital ϴ for similar measurements with slightly different implications. In this case O( n ) would be pronounced "big oh of n", o( n ) "little oh of n", and ϴ(n) "theta of n".

That is commonly referred to as Big O Notation, and since my days as a math/CS student I have always pronounced it (and heard it pronounced) as "Big O of n", "Big O of n log n", etc.

I think it's also common to just say "oh" followed by whatever is inside the parentheses.

Examples:

There is an "oh n log n" algorithm for that problem

Doesn't that require "oh n squared" time in the worst case?