title: Plot generated in Octave is fully black
body: <p>I am using <strong>octave 4.2.1</strong> on <strong>fedora 26</strong>.</p>
  
  <p>(I recently upgraded from fedora 25 to 26 and through this octave was upgraded from 4.0.3 to 4.2.1)  </p>
  
  <p>Now when I plot a figure like <code>plot(x)</code>the figure that comes up is just a black image. Before the up gradation i didn't had this problem.
  I am attaching a snapshot also</p>
  
  <p><a href="https://i.stack.imgur.com/cu7Gw.png" rel="noreferrer"><img src="https://i.stack.imgur.com/cu7Gw.png" alt="enter image description here"></a>.</p>
  
  <p>How can i correct it? </p>