> nor does it expand the program into a mathematical formula. Meh, this is not entirely accurate. Sure it doesn't expand the program into analytic functions wh

> nor does it expand the program into a mathematical formula. Meh, this is not entirely accurate. Sure it doesn't expand the program into analytic functions whose derivatives are easy to compute; but it still handles the program symbolically. So, in a way, it still transforms the program into a known set of mathematical primitives of which it can then construct a program that computes the derivative in compile time.