title: figsize does not work for matplotlib 3d plot
body: <p>I plotted 2 figures, here is the screenshot</p>
  
  <p><a href="https://i.stack.imgur.com/eXnmn.png" rel="nofollow noreferrer">figsize</a></p>
  
  <p>the one (2D) on top is rendered as expected.
  the one (3D) on bottom is not, the figure is so small!</p>
  
  <p>setting the value of <code>figsize</code> does not work.</p>
  
  <p>figsize=(3,3) and figsize=(13,13) give the same result!</p>
  
  <p><code>%matplotlib inline</code> rendered same way. </p>
  
  <p>I tried different browsers, clear the cache, dose not work either.</p>
  
  <p>I guess some rcParams control this, because this is reproducible only on my mac, but I don't have a clue to find it!</p>
  
  <p>any clue will be appreciated.</p>
  
  <p>whole coding:</p>
  
  <pre><code>%pylab inline
  from mpl_toolkits.mplot3d import Axes3D
  fig = plt.figure(figsize=(3,3))
  ax = fig.gca(projection='3d')
  ax.scatter(0.5, 0.5, 0.5, marker = '^')
  </code></pre>