33 lines
875 B
Python
33 lines
875 B
Python
import matplotlib.pyplot as plt
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import numpy as np
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from math import comb
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def B(n, k, t):
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return comb(n, k) * t**k * (1 - t)**(n - k)
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P = np.array([[0, 0], [0, 2], [1, 2], [1, 0], [1, -2], [2, -1], [2, 0]])
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n = 3
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S1 = np.array([sum(P[k] * B(n, k, t) for k in range(n + 1)) for t in np.linspace(0, 1, 100)])
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S2 = np.array([sum(P[k + n] * B(n, k, t) for k in range(n + 1)) for t in np.linspace(0, 1, 100)])
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S1p = np.array([n * sum((P[k + 1] - P[k]) * B(n - 1, k, t) for k in range(n)) for t in np.linspace(0, 1, 100)])
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S2p = np.array([n * sum((P[k + 1 + n] - P[k + n]) * B(n - 1, k, t) for k in range(n)) for t in np.linspace(0, 1, 100)])
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plt.subplot(121)
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plt.plot(S1[:,0], S1[:,1])
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plt.plot(S2[:,0], S2[:,1])
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plt.plot(P[:,0], P[:,1], 'ro')
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plt.axis('equal')
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plt.subplot(122)
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plt.plot(S1p[:,0], S1p[:,1])
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plt.plot(S2p[:,0], S2p[:,1])
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plt.axis('equal')
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plt.show()
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