np.sin(4 * np.pi * x)
fig, (ax1, ax2, ax3) = plt.subplots(3, 1, sharex=True, figsize=(6, 6))
ax1.fill_between...(x, y1)
ax1.set_title('fill between y1 and 0')
ax2.fill_between(x, y1, 1)
ax2.set_title('fill between...y1 and 1')
ax3.fill_between(x, y1, y2)
ax3.set_title('fill between y1 and y2')
ax3.set_xlabel('x')...x.mean())**2 / np.sum((x - x.mean())**2))
fig, ax = plt.subplots()
ax.plot(x, y_est, '-')
ax.fill_between...x.mean())**2 / np.sum((x - x.mean())**2))
fig, ax = plt.subplots()
ax.plot(x, y_est, '-')
ax.fill_between