On the journey to Paris he had visited Gauss in Göttingen. Jacobi's fundamental work on the theory of elliptic functions, which had so impressed Legendre, was based on four theta functions.
Sa mga paglalakbay sa Paris niya binisita gauss sa Gottingen. Jacobi's pangunahing trabaho sa teorya ng tambilugin function, kung saan nagkaroon kaya impressed Legendre, ay batay sa apat na theta function.