中文说明：
牛顿法又称牛顿-拉弗森方法（Newton-Raphson method），是一种在实数域和复数域上近似求解方程的方法。本程序收敛速度快，迭代步数可取大一些。
English Description：
< p > Newton method is also called Newton method - Raphson method (Newton method) - The Raphson method is a method of approximate solving equations in real number field and complex number field. The convergence speed of this program is fast, and the number of iteration steps can be larger.