Thanks for the quick reply! I'm actually not trying to figure out how to compute the inverse of a function (with this much, I'm set!). What I'd like to do is to be able to sketch functions of y as opposed to functions of x.
For example, x=y^2 isn't a function of x since each x is associated with two different y values: (1,1) and (1,-1). In addition, I'd love to be able to sketch an equation such as x=4, which is a vertical line (again...sorry if I don't know how much of a math background you have!) but again, not a function of x since each x has an infinite number of y's associated with it.
Anyway, I appreciate that this is a bit of a "mathy specific" question so if there's isn't an "easy" solution out there, I'd very much understand. However, any other thoughts would be appreciated.