Definition talk:Complex Number

This isn't really about this page, but I wasn't sure where to put it, and this page made me think of it. Should we have a definition of $\operatorname{cis}\;\theta=\cos\theta+i\sin\theta$? And if so, is it an abbreviation for a word, or just cosine i sine? --Cynic (talk) 19:47, 1 February 2009 (UTC)

I was wondering about this as well. I wondered whether to mention it in this page in passing as an aside, or whether we ought to set up a separate page defining the polar form of a complex number in its own right. Thoughts? --Matt Westwood 21:38, 1 February 2009 (UTC)

I imagine that any proof we want to put up will simply use $re^{i\theta} \ $, with the fact that this is equivalent to a polar form understood. Thus, the only time we would need to use anything like a "polar form" or cis would be in demonstrating that $re^{i\theta} \ $ is in fact valid in that sense. Since these things will only appear in a single proof and not be referred to constantly, I don't see any problem with keeping the polar form here as a subsection of this page. It also seems like we could sidestep cis entirely, as it has fallen into disuse with many modern student and reference texts. Zelmerszoetrop 09:34, 2 February 2009 (UTC)