Question

Anyone know the symbol that means undefined?

Answer 1

I don't think there is a symbol for undefined, but it is usually abbreviated to undef.
If you're talking about things being undefined because there is no unique limit, then you can use DNE for "does not exist" (referring to the limit).

Answer 2

Thanks my teacher is very picky with notation and im sick and tired of writing undefined so many times. I will just use DNE instead.

Answer 3

Ok, but if your teacher is picky, please know the difference in meaning between, "undefined" and "does not exist."

Answer 4

You're probably better off with "undef."