Grapheur
You can graph functions on a 2D axis plan.
Start by selecting the grapher tool button which will popup the function grapher.
You can input your function equations separated by comas ; in the input text area at the bottom of the window. The x (min,max) interval as well as the y interval can also be set.
The functions are drawn in real time as you type, the same goes for intervals the x and y axis steps automatically scale.
Once you are done you can add the diagram to the board.
