# !/usr/bin/env python
# -*- coding: utf-8 -*-
"""
@Author: P♂boy
@License: (C) Copyright 2013-2017, Node Supply Chain Manager Corporation Limited.
@Contact: 17647361832@163.com
@Software: Pycharm
@File: sqrt.py.py
@Time: 2018/11/19 16:22
@Desc:牛顿迭代法求一个数的平方根
1对给定正实数x和允许误差e，令变量y取任意正实数值，如另y=x
2如果y*y与x足够接近， 即|y*y-x|<e,计算结束并把y作为结果
3取z=(y+x/y)/2
4将z作为y的新值，回到步骤1
"""
import math
def sqrt(x):y = xwhile abs(y * y - x) > 1e-6:y = (y + x / y) / 2return yprint(sqrt(5))
print(math.sqrt(5))

结果