说明：  Newton-Raphson法的介绍，包括原理，迭代方程，收敛性，优缺点，以及一个应用示范
(The Newton-Raphson method, or Newton Method, is a powerful technique for solving equations numerically. Like so much of the dierential calculus, it is based on the simple idea of linear approximation. The Newton Method, properly used, usually homes in on a root with devastating eciency. The essential part of these notes is Section 2.1, where the basic formula is derived, Section 2.2, where the procedure is interpreted geometrically, and|of course|Section 6, where the problems are. Peripheral but perhaps interesting is Section 3, where the birth of the Newton Method is described.)