because of the ~~(mis?)~~use of the word “contradictory”,

I used that only in my second comment, after the first person got flustered :) Go up two more in the comment chain and you'll see my original comment. Although, I stand by the second comment as well - the article is contradicting itself.

If I say

The square root of -1 is i [...] The square root of -1 is not defined. [..]

Only to THEN go on to explain what imaginary numbers are, then I have still contradicted myself :)