title: Matplotlib LaTeX: Inconsistent Behaviour with Greek Letters (Specifically \rho)
body: <p>I'm trying to add some axis-labels to a graph which contains the Greek letter 'rho'. To do this I want to use the LaTeX capability of Matplotlib but it seems to have a problem with the \rho symbol.</p>
  
  <p>Here is a minimal example:</p>
  
  <pre><code>import matplotlib.pyplot as plt
  from matplotlib import rc,rcParams
  
  rc('text',usetex=True)
  rcParams.update({'font.size': 16})
  
  plt.plot([0,1,2,3,4],[0,1,4,9,16])
  plt.xlabel('\rho A_i') # works if \rho is replaced with, for example, \sigma
  plt.ylabel('Something else')
  plt.show()
  </code></pre>
  
  <p>Upon running the first time I get a bunch of LaTeX errors and a blank figure window, running again shows the graph but the xlabel reads '<em>ho Ai</em> ' where the <em>i</em> is subscript as expected.</p>
  
  <p>The weird thing is if I replace <code>\rho</code> with something else, say, <code>\sigma</code> it shows up correctly. Can anybody tell me why it is not happy with my code example and how to fix it?</p>
  
  <p>Thanks.</p>
  
  <p>P.s. I tried putting the expression in <code>$..$</code> but that changed nothing.</p>