Infinitesimal calculus

Infinitesimal calculus is an area of mathematics pioneered by Gottfried Leibniz based on the concept of infinitesimals, as opposed to the calculus of Isaac Newton, which is based upon the concept of the limit. Because infinitesimals were not put on a rigorous mathematical basis until the second half of the twentieth century, the delta-epsilon definition of limits and calculus became standard.

See also

Calculus, nonstandard analysis, nonstandard analysis and hyperreal infinitesimals