Graphing Calculator

This is a graphing calculator that I made to apply to a high school.

If you want to create a function then click the add button then click expression. 

You can only:

use functions with y= at the start like "y = 3x" or "y= 2 + x * x"

use functions that arnt recursive unlike "y= xy"

use basic components like "y = x*x" and unlike "y=x^2"