{\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.
Amended documents, when properly executed (signed by all parties concerned), retain the legal validity of the original document. For construction or supply contracts, amendment refers to change made before the contract is awarded, any change made afterwards is called modification.