I need to be able to set f(x) to user input in my program. For example the user inputs x^3-3. Then later in the program, a transformation can be applied to the function by using something like f(2x). The output of f(2x) would be 8*x^3-3. I am having trouble doing this though. I get user input with something such as Input "Enter a function:", fx and apply this value to the function with Define f(x) = fx. Now I will illustrate the problem with this. If a user inputs something such as x^2-2, if I call f(2x) it just returns x^2-2 as if I called f(x). I have tried many things such as Define f(x) = expr(fx), Define f(x) = eval(fx), and even pre-defining f(x) as x, and using f(x)->f(fx), but none of these things worked. Is there a function that makes this work?
After a long time I realized that Ti-basic doesn't support function composition. There isn't really a way around it.