# -*- coding:utf-8 -*-

import numpy as np
import matplotlib as mpl
import matplotlib.pyplot as plt
import math

def func(a):
	if a < 1e-6:
		return 0
	last = a
	c = a/2
	while math.fabs(c - last) > 1e-6:
		last = c
		c = (c + a/c) / 2
		return c

if __name__ == '__main__':
	mpl.rcParams['font.sans-serif'] = [u'SimHei']
	mpl.rcParams['axes.unicode_minus'] = False 
	x = np.linspace(0,30,num=50)
	fun_c = np.frompyfunc(func, 1, 1)
	y = fun_c(x)
	plt.figure(figsize=(10,5),facecolor='w')
	plt.plot(x,y,'ro-',lw=2,markersize=6)
	plt.grid(b=True,ls=':')
	plt.xlabel(u'X',fontsize=16)
	plt.ylabel(u'Y',fontsize=16)
	plt.title(u'这是啥？',fontsize=18)
	plt.show()