I was wondering if there is a way to create a function that follows a regular equation (for example y = 1 + x) when $x$ is smaller than 3, but ends in nothing or null when $x$ becomes larger than 3.
The equation thus simply just stops.
What would I put down in the piecewise function: $null$, $ε$ (empty string), $NaN$ ..? What is a good mathematical way of writing down this function?
As an example of what it could be:
$y=\left\{\begin{array}{ll}null & x> 3\\1+x & x\le 3\end{array}\right.$
Screenshot of graph for example equation
Thanks, Mudi