# Omgekeerde paraboloïde

import matplotlib.pyplot as plt
import numpy as np

from matplotlib import cm, colors
from mpl_toolkits.mplot3d import Axes3D

phi, theta = np.mgrid [0:2 * np.pi:720j, np.pi / 2:np.pi:90j]

r = 4
x = r * np.cos (phi) * np.sin (theta)
y = r * np.sin (phi) * np.sin (theta)
z = 4 - x**2 - y**2

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

ax = fig.add_subplot (111, projection = "3d")

ax.plot_surface (x, y, z, alpha = 0.2, linewidth = 0.1)

ax.set_xlim ([ -4.0, 4.0])
ax.set_ylim ([ -4.0, 4.0])
ax.set_zlim ([-12.0, 4.1])

ax.plot_wireframe (x, y, z, color = "sandybrown")

plt.show ()