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- import numpy as np
- def lagrange(points):
- result = np.poly1d([0])
- for i, (x_i, y_i) in enumerate(points):
- poly = np.poly1d([y_i])
- for j, (x_j, y_j) in enumerate(points):
- if i == j:
- continue
- poly *= np.poly1d([1, -x_j]) / (x_i - x_j)
- #print(poly)
- #print(poly(1), poly(2), poly(3))
- result += poly
- return result
- left = lagrange([
- (1, 2), (2, 2), (3, 6)
- ])
- print(left)
- right = lagrange([
- (1, 1), (2, 3), (3, 2)
- ])
- print(right)
- out = lagrange([
- (1, 2), (2, 6), (3, 12)
- ])
- print(out)
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