Not only had he made major contributions to difference equations and differential equations but he had examined applications to mathematical astronomy and to the theory of probability, two major topics which he would work on throughout his life.
Hindi lamang nagkaroon siya ginawa malaking kontribusyon sa pagkakaiba equation at kaugalian equation ngunit niya napagmasdan mga aplikasyon sa matematika astronomy, at sa palagay ng mga bagay na maaaring mangyari, dalawang malaking paksa na kung saan siya ay gumagana sa lahat ng dako ng kanyang buhay.