title: Strange behavior of Matplotlib plotting numpy.matrix types
body: <p>I have the result of some computations made with <code>numpy.matrix</code> types</p>
  
  <pre><code>import numpy as np
  import matplotlib.pyplot as plt
  
  from mpl_toolkits.mplot3d import Axes3D
  
  fig = plt.figure()
  ax = Axes3D(fig)
  
  # [...]
  
  # Downsampling for plotting
  # type(verts):  np.matrix
  # verts.shape:  (3, 700000)
  
  verts = verts_small[:, ::1000]
  
  ax.plot(verts[0, :], verts[1, :], verts[2, :], 'o')
  </code></pre>
  
  <p>This has strange behavior. Plots the points all in a line.</p>
  
  <p>If instead:</p>
  
  <pre><code>verts = np.array(verts[:, ::1000])
  </code></pre>
  
  <p>the 3D-plot works as expected. Is this an intended behavior or is it a bug?</p>