{\displaystyle \int _{a}^{b}\!f(x)\,dx=F(b)-F(a).} The principles of integration were formulated independently by Isaac Newton and Gottfried Leibniz in the late 17th century, who thought of the integral as an infinite sum of rectangles of infinitesimal width.
amendment - a statement that is added to or revises or improves a proposal or document (a bill or constitution etc.) statement - a message that is stated or declared; a communication (oral or written) setting forth particulars or facts etc; according to his statement he was in London on that day.
An amendment is more commonly used than an addendum. In simple words, amendment means making changes in an already existing agreement. On the other hand, Addendum means including an additional document in the already existing one. An amendment can also be called as correcting a document or improving the document.