绘制 A 3D 双曲面

Question

My teacher in class gave this formula −0.3 **2−0.3 **2+ **2=1.

and showed its 3d graphic in class seen below. I just perform a half graphic, and I have no idea how to plot the rest graphic. The following code from matplotlib import cm import matplotlib.pyplot as plt import numpy as np

X = np.linspace(-5, 5, 100)
Y = np.linspace(-5, 5, 100)
X, Y = np.meshgrid(X, Y)

Z = np.sqrt(0.3*(X **2 + Y **2) + 1)
ax = plt.gca(projection='3d')
plot1 = ax.plot_surface(X, Y, Z, cmap='jet', alpha=0.6, vmin=-5, vmax=5)
plt.colorbar(plot1)

plt.show()

enter image description here

Answer 1

This is because when you change the expression about the z-axis, the result is positive no matter what value you substitute for x,y because of the square. Just adding -Z values is a simple solution.

ax.plot_surface(X, Y, Z, cmap='jet', alpha=0.6, vmin=-5, vmax=5)
ax.plot_surface(X, Y, -Z, cmap='jet', alpha=0.6, vmin=-5, vmax=5)