A simple (though somewhat pedantic) question: when using big O notation in a sentence, should it be preceded with "a" or "an"? Example:
The extra loop results in a/an $\mathcal{O}(N)$ increase in cost.
The ubiquitous Cormen textbook notes on page 47:
For a given function $g(n)$, we denote by $\mathcal{O}(g(n))$ (pronounced “big-oh of g of n” or sometimes just “oh of g of n”)
which would seem to indicate "a" should precede something pronounced "big-oh". Later on the same page, however, the textbook uses the phrase "an $\mathcal{O}(n^2)$ upper bound." Which is used more in the literature? It seems like a triviality, but as someone working on the edge of theoretical computer science from a primary focus on another field, I'd like not to sound like an outsider.