#Python代码以实例展示求解方程的根。
import  math
def f(x):
    return math.pow(x,3)-9*x+1       
def fd(x):
    return  3*math.pow(x,2)-9

def newton_method(n,x):
    times = n
    next_x = 0
    y= f(x)
    yd = fd(x)
    print('y= ' , y, ',yd = ' , yd , ',times = ' ,times)
    next_x = x - y/yd
    print('next:',next_x)
    if abs(y - f(next_x)) < 1e-6 : 
        print("next:",next_x)
    else:
        next_x=x-y/yd
        return newton_method(n+1,next_x)

newton_method(0,4.1)