# coding:utf-8

import numpy as np

import matplotlib.pyplot as plt

x = np.arange(-5/2,5/2,0.01)

y = -x**3+x**2+np.e+x**4

dy = lambda x:-3*x**2+2*x+4*x**3

dyy = lambda x:-6*x+2+12*x**2

a = 0.001

def sgd_func(n):

    x0=-10

    ady = []

    for i in range(n):

        # x0 = x0 -a*dy(x0)

        x0 = x0 - dy(x0)/dyy(x0)

        ady.append(x0)

    return x0,ady

x0,ady = sgd_func(10)

y0 = x0**2+x0+np.e

plt.subplot(1,2,1)

plt.plot(ady)

plt.subplot(1,2,2)

plt.plot(x,y)

plt.text(x0,y0,'* min_value')

plt.show()