>>> """
======================
Triangular 3D surfaces
======================

Plot a 3D surface with a triangular mesh.
"""
... 
... import matplotlib.pyplot as plt
... import numpy as np
... 
... 
... n_radii = 8
... n_angles = 36
... 
... # Make radii and angles spaces (radius r=0 omitted to eliminate duplication).
... radii = np.linspace(0.125, 1.0, n_radii)
... angles = np.linspace(0, 2*np.pi, n_angles, endpoint=False)[..., np.newaxis]
... 
... # Convert polar (radii, angles) coords to cartesian (x, y) coords.
... # (0, 0) is manually added at this stage,  so there will be no duplicate
... # points in the (x, y) plane.
... x = np.append(0, (radii*np.cos(angles)).flatten())
... y = np.append(0, (radii*np.sin(angles)).flatten())
... 
... # Compute z to make the pringle surface.
... z = np.sin(-x*y)
... 
... ax = plt.figure().add_subplot(projection='3d')
... 
... ax.plot_trisurf(x, y, z, linewidth=0.2, antialiased=True)
... 
... plt.show()
...