习题2.11

习题2.11代码

import numpy as np
import pandas as pd
import sympy as sp
sp.init_printing(use_unicode=True)
import matplotlib.pyplot as plt
plt.rcParams['font.sans-serif']=['Times New Roman + SimSun + WFM Sans SC']
plt.rcParams['mathtext.fontset']='cm'
# Times New Roman + SimSun + WFM Sans SC
# simsum宋体, times new roman -*, simhei黑体, kaiti楷体,
# dengxian等线, fangsong仿宋, Microsoft Yahei微软雅黑
plt.rcParams['axes.unicode_minus']=False
plt.rcParams['figure.dpi'] = 200
# plt.rcParams['figure.figsize'] = [4, 3]
# plt.rcParams['font.size'] = 12
plt.rcParams['xtick.direction'] = 'in'
plt.rcParams['ytick.direction'] = 'in'
f = lambda x: (np.abs(x+1) - np.abs(x-1))/2 + np.sin(x)
g = lambda x: (np.abs(x+3) - np.abs(x-3))/2 + np.cos(x)
eqs = lambda x: [
    2*x[0] - 3*f(x[2]) - 4*g(x[3]) + 1,
    3*x[1] - 2*f(x[2]) - 6*g(x[3]) + 2,
    x[2] - f(x[0]) - 3*g(x[1]) + 3,
    5*x[3] - 4*f(x[0]) - 6*g(x[1]) + 1
]

from scipy.optimize import least_squares
s = least_squares(eqs, np.random.randn(4))
print(s)