# Vlak

import matplotlib.pyplot as plt
import numpy as np

plt.figure (figsize = (8, 8))

ax = plt.axes (projection = "3d")

x = np.arange (-2, 2, 0.05)
y = np.arange (-2, 2, 0.05)

x, y = np.meshgrid (x, y)
z = 3
G = 2 * x**2 - y**2 + z**2

ax.plot_surface (x, y, G, color = "purple")

plt.show ()