技術標籤：非線性方程組

from matplotlib import pyplot as plt
import numpy as np


def fun(x):
    return x**3-2*x-5


def dfun(x):
    return 3*x*x-2


def newton(fun,dfun,a,b,eps):
    err = 1
    x = b
    k = 0
    lada = 1
    x_r = []
    while err > eps:
        x_r.append(x)
        x = x - lada * fun(
 
x)/dfun(x)
        err = fun(x)
        k = k + 1
        lada = lada * 0.99
    print('牛頓下山法的迭代次數為{:d}次'.format(k))
    print('x的迭代過程：')
    for i in x_r:
        print('{:.7f}'.format(i), end='  ')
    print(' ')
    return x


x = newton(fun, dfun, 0, 10, 0.0000001)
print('牛頓下山迭代法的求解結果為{:.7}'.format(x))
x1 =
 
 np.linspace(-10, 10, 1000)
y1 = fun(x1)
plt.plot(x1, y1)
plt.show()