173-1-（2）

import numpy as np
import pylab as pl
from scipy.interpolate import lagrange
import matplotlib.pyplot as plt

xi = np.linspace(-1, 1, 10)
yi = 1 / (1 + 25 * xi * xi)

x = np.linspace(-1, 1, 100)
p = lagrange(xi, yi)

plt.xlabel(u'x')
plt.ylabel(u'y')
plt.plot(xi, yi, "o", label=u"date")
plt.plot(x, p(x), label=u"lagrange interpolation")
pl.legend()
pl.show()