自学教程：python实现拉格朗日插值及作图

import numpy as npimport matplotlib.pyplot as pltX = input("x的值：").split(' ')Y = input("y的值：").split(' ')x = input("要预测的值：")print('/n')X = np.array(X).astype(np.float64)Y = np.array(Y).astype(np.float64)x = np.array(x).astype(np.float64)n = len(X)# 原函数def fun(x): return np.sin(x)# 累乘函数def T(x, i, X): T_i = 1 for x_i in X:  if X[i] == x_i:   continue  T_i = T_i * (x-x_i) return T_i# 插值基函数def P(i, x, X, Y): P_i = T(x, i, X)/T(X[i], i, X) * Y[i] return P_i# 计算预测值def L(x, X, Y): result = 0 for i in range(n):  result = result + P(i, x, X, Y) return resulty = L(x, X, Y)   print("预测结果：" + str(y) + '/n')print("误差：" + str(fun(x) - y))# 画图X_n = np.linspace(0, 1, 50)Y_n = fun(X_n)x_n = np.linspace(0, 1, 50)y_n = L(x_n, X, Y)l1, = plt.plot(X_n, Y_n, label='theory')l2, = plt.plot(x_n, y_n, label='prediction',linestyle='--')plt.legend(handles=[l1,l2,],labels=['theory','prediction'], loc='best')plt.show()