While in college, I wrote a program that did this. I thought I needed precise derivatives for a curve fitting program, so I wrote one that evaluated an expressi

While in college, I wrote a program that did this. I thought I needed precise derivatives for a curve fitting program, so I wrote one that evaluated an expression and all of its derivatives, all at once. This was typical noobie chutzpah. First, I converted an infix expression into its postfix form using a textbook algorithm. Then I applied all of the differentiation rules to the postfix expression, including L'Hospital's rule. Was it correct? All I know is that I couldn't kill it.