>>> """
================
Parametric Curve
================

This example demonstrates plotting a parametric curve in 3D.
"""
... 
... import numpy as np
... import matplotlib.pyplot as plt
... 
... 
... ax = plt.figure().add_subplot(projection='3d')
... 
... # Prepare arrays x, y, z
... theta = np.linspace(-4 * np.pi, 4 * np.pi, 100)
... z = np.linspace(-2, 2, 100)
... r = z**2 + 1
... x = r * np.sin(theta)
... y = r * np.cos(theta)
... 
... ax.plot(x, y, z, label='parametric curve')
... ax.legend()
... 
... plt.show()
...