title: Save plot to png with Octave
body: <p>I have just started with Octave and I'm trying to plot something to a png. The plot appears correctly on the screen when I run the script, but the output of the png is completely black. Here's a MWE:</p>
  
  <pre><code>clear all
  kym=1:10
  pcs=1:10
  aux=figure();
  plot(kym,pcs,'k-')
  fname = 'mwe.png';
  saveas(aux, fname, 'png');
  </code></pre>
  
  <p>This code outputs the following png:
  <a href="https://i.stack.imgur.com/4yOeM.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/4yOeM.png" alt="enter image description here"></a></p>
  
  <p>Which is obviously not correct. There is also a warning output when running the code:</p>
  
  <pre><code>warning: print.m: fig2dev binary is not available.
  Some output formats are not available.
  warning: called from
      __print_parse_opts__ at line 385 column 9
      print at line 291 column 8
      saveas at line 105 column 3
      mwe at line 7 column 1
  </code></pre>
  
  <p>Google was of little help with this one. Any ideas?</p>
  
  <p>I'm using octave version 4.0.0 on a Linux Mint 18.</p>