How might I make my script perform differentiation on a user-defined function? I also want the function and its derivative (in the form of a function) to be applied throughout the script, say in the forms of f and f' respectively, which I believe requires str2func. Example: The user is prompted for an f(x). He enters x^3. Then both x^3 and 3*x^2 are applied in the place of f and f' throughout the script. Thanks in advance!