)
Systematic approach to the theory of Calculus began in the 17th century In 1665, Newton began his work on the Calculus described by him as the theory
of fluxions and used his theory in finding the tangent and radius of curvature at
any point on a curve Newton introduced the basic notion of inverse function
called the anti derivative (indefinite integral) or the inverse method of tangents During 1684-86, Leibnitz published an article in the Acta Eruditorum
which he called Calculas summatorius, since it was connected with the summation
of a number of infinitely small areas, whose sum, he indicated by the symbol ‘∫’