cubicS.py

from scipy.interpolate import interp1d
import numpy as np
import matplotlib.pyplot as plt

a = 0
b = 10

linear_gains = (b - a) / 16

li = lambda x: a + linear_gains * x

xs = [0, 6, 8, 10, 16]
ys = [a, li(2), li(8), li(14), b]

cubic = interp1d(xs, ys, kind='cubic')
space = np.linspace(start=0, stop=16, num=16)

plt.plot(space, cubic(space))
plt.scatter(xs, ys)
plt.show()