I asked a question about applying the chain rule to the original theory of Infinitesimal Calculus (as Leibniz originally defined it). I provided an answer based on feedback. Does anyone know if this answer is correct? If not, does anyone have an example of applying the chain rule using non-standard analysis?
I'm interested how Calculus was used in Leibniz's era and how close the results are to the modern limit theory. For example, using his differential notation appears useful for cancelling out long chains, making calculations easier.