Fundamental Theorem of Calculus

When it comes to understanding the concept of the fundamental theorem of calculus, two names are prominent: Isaac Newton and Gottfried Leibniz. Although either one of these mathematicians can possibly be credited with the development of the fundamental theorem of calculus, it is true to say that neither was the first to do so. The first published work on the fundamental theorem was by James Gregory, known to Newton. Earlier known work was by Pierre de Fermat. By 1666, Newton made free use of algebra and a variety of algorithmic devices and notations in formulating a systematic method of differentiation.

It was while Newton was working on infinite series that he composed, in 1669, "De analysi per aequationes numero terminorum infinitas" (pub. 1711). In that volume, Newton presented the first systematic account of his chief mathematical work: the calculus. Newton’s work here was not far removed from that published by Isaac Barrow (the most important of Newton’s mentors) in 1670. Newton’s notation was close to Barrow’s. Newton circulated De analysi among friends—to Leibniz and Oldenburg—but refrained from publishing it until 1687 in Philosophiae naturalis principia mathematica, the most admired scientific treatise of all times.

The inverse of differentiation is integration. Newton’s prime contribution was in the consolidation of differentiation and integration into a general algorithm applicable to all functions, whether algebraic or transcendental. In the first edition of Principia (1687), Newton admitted that Leibniz possessed a similar method. In the third edition of 1726 (published when Newton was age 83 and following the bitter quarrel between adherents of Newton and Leibniz concerning the independence and priority of the discovery of the calculus), Newton deleted the reference to the calculus of Leibniz. Newton’s discovery came before that of Leibniz (by about ten years), but the discovery by Leibniz was independent of that of Newton. Moreover, Leibniz is entitled to priority of publication because he printed an account of his calculus in 1684 in the Acta Eruditorum (compared to July 5, 1687 edition).

By 1676, Leibniz had arrived at the same conclusion that Newton had reached several years earlier: He possessed a method that was highly important due to its generality. Leibniz therefore developed an appropriate notation, still used today. He fixed on dx and dy for the smallest possible differences (differentials) in x and y. He introduced the symbol ∫—an enlarged letter s for sum—in integral calculus: ∫ y dx. In his 1684 publication, Leibniz introduced the following formulae

98418314-97252.jpg

for products, quotients, and powers (or roots). These formulae were derived by neglecting infinitesimals of higher order.

In 1716, Leibniz challenged Newton (then age 73) to find the orthogonal trajectories of a one-parameter family of plane curves. Within a few hours, despite his age, Newton solved the problem and gave a general theorem for the task.

Bibliography

Cruz-Filipe Luìs. "A Constructive Formalization of the Fundamental Theorem of Calculus." Lecture Notes in Computer Science 2646 (2003): 108-26.

Körner , Thomas W. Calculus for the Ambitious. New York: Cambridge UP, 2014.

Ross, Kenneth A. Elementary Analysis: The Theory of Calculus. 2nd ed. New York: Springer, 2013.

Sobczyk, Garret, and Omar L. Sànchez. "Fundamental Theorem of Calculus." Advances in Applied Clifford Algebras 21 (2011): 221-31.