程序文件ex7_3.py

import numpy as np
import pylab as plt
from scipy.interpolate import lagrange

yx = lambda x: 1/(1+x**2)

def fun(n):
x = np.linspace(-5, 5, n+1)
p = lagrange(x, yx(x)) # n次插值多项式
return p

x0 = np.linspace(-5, 5, 100)

plt.rc('text', usetex=True) #使用LaTeX字体

plt.rc('font', size=15); N = [6, 8, 10]

plt.style.use('default')
N=[6,8,10]
s = ['--*b', '-.', '-p']
for k in range(len(N)):
p = fun(N[k]); plt.plot(x0, np.polyval(p,x0),s[k])
plt.plot(x0, yx(x0));
plt.legend(['\(n=6\)', '\(n=8\)', '\(n=10\)', '\(1/(1+x^2)\)'])
plt.show()

print("学号后四位：3004")