All of tb148's Comments + Replies

Yes, that sounds much more normal to me. Though in the particular case here, something else seems off: when you write f(x) you would normally italicize both the "f" and the "x", as you can see in the rendering in this very paragraph. I can't think of any situation in actual mathematical writing where you would italicize one and not the other in order to make some distinction between function-names and variable names. For that matter, I'm not wild about making a distinction between "variables" and "functions". If you write f(x) and also sin(x) then it would be normal for "f" and "x" to be italicized and not "sin". I was going to say that the reason is that f and x are in fact both variables, and it just happens that one of them takes values that are functions, whereas sin is a fixed function and you'll never see anything like "let sin = 3" or "let sin = cos" -- but actually that isn't quite right either, because named mathematical constants like e are usually italicized. I think the actual distinction is that single-letter names-of-things get italicized and multiple-letter ones usually don't.