What is the conventional name/notation for the function $ N(n) = \begin{cases} 1 & n \le 0 \\ n & n > 0 \end{cases}$?

Question

I am wonder what the conventional name/notation for this function:

$$ N(n) = \begin{cases} 1 & n \le 0 \\ n & n > 0 \end{cases}$$

I assume its use is frequent enough that there is such a thing. If not, I'll simply define it like I have above.