title: mplot3d tutorial examples are not running as they should
body: <p>I'm running into an issue when trying to run <a href="http://matplotlib.org/mpl_toolkits/mplot3d/tutorial.html#tri-surface-plots" rel="nofollow noreferrer">standard matplotlib examples from the documentation</a>. For the plotting of a trisurface using <code>plot_trisurf</code> for the pringle example, two errors occur: </p>
  
  <ol>
  <li><p>a single error: </p>
  
  <pre><code>/Library/Python/2.7/site-packages/matplotlib-override/matplotlib/collections.py:764: RuntimeWarning: invalid value encountered in sqrt   scale = np.sqrt(self._sizes) * dpi / 72.0 * self._factor
  </code></pre></li>
  </ol>
  
  <p>and </p>
  
  <ol start="2">
  <li><p>an error for each point:</p>
  
  <pre><code>Jul 28 11:12:13  python[77168] &lt;Error&gt;: void CGPathCloseSubpath(CGMutablePathRef _Nullable): no current point.
  </code></pre></li>
  </ol>
  
  <p>I'm using matplotlib 1.5.1
  Here's the source/example code that I'm using: </p>
  
  <pre><code>from mpl_toolkits.mplot3d import Axes3D
  from matplotlib import cm
  import matplotlib.pyplot as plt
  import numpy as np
  
  n_angles = 36
  n_radii = 8
  
  # An array of radii
  # Does not include radius r=0, this is to eliminate duplicate points
  radii = np.linspace(0.125, 1.0, n_radii)
  
  # An array of angles
  angles = np.linspace(0, 2*np.pi, n_angles, endpoint=False)
  
  # Repeat all angles for each radius
  angles = np.repeat(angles[..., np.newaxis], n_radii, axis=1)
  
  # Convert polar (radii, angles) coords to cartesian (x, y) coords
  # (0, 0) is added here. There are 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())
  
  # Pringle surface
  z = np.sin(-x*y)
  
  fig = plt.figure()
  ax = fig.gca(projection='3d')
  
  ax.plot_trisurf(x, y, z, cmap=cm.jet, linewidth=0.2)
  
  plt.show()
  </code></pre>
  
  <p>and here is the plot: </p>
  
  <p><a href="https://i.stack.imgur.com/TcXa3.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/TcXa3.png" alt="enter image description here"></a></p>