Grapher

a) red b) blue c) yellow d) green Also, to be able to read in dynamic equations, there are several routes you could go. One is to build a simple parser for the the input (which would not be very simple to code probably). The other that I can think of is to implement a drag and drop interface for math operations so that you know for certain what has been entered. For example, to add two expressions, you could have a icon to drag in that has two placeholders for the expressions on either side of the "+" symbol, kind of like so: 2x == () * () -> (2) * (x) 2(x+1) == () * (() + ()) -> (2) * ((x)+(1)) That way, you know what the equation parses to in advance because you force it to behave that way. The other way I can think of, and probably the easiest is to implement is a parser that uses prefix, function notation. So your equation c for example could be written like so: subtract( sqrt( abs( mult(x,10) ) ) , 10 ); Of course, that looks a bit messier, but it's one of the easier ways to do it. I hope this was helpful.

@supermagicmilk sorry for the late reply! i think i will use RPN for the parser, so now im working with the RPN parser (but first in different scenario!) :D