title: Multiple plot calls in octave
body: <p>I'm working in octave, I need to call <code>plot3</code> two or more times to produce one graph. But it only plots the last call of <code>plot3</code>. I need some help.</p>
  
  <p>This is my code:
  It only plots the line <code>plot3(tras(1), tras(2), tras(3), 'bo');</code></p>
  
  <pre><code>    p = [   0.0,    0.0,    0.0
            500.0,    0.0,    0.0
            500.0, -500.0,    0.0
              0.0, -500.0,    0.0
              0.0,    0.0,    0.0];
      mano = [119.818542 -43.371277 50.230591 1];
  
  Tinv = [
   0.998891 -0.001007 0.047065 64.223625
   0.000000 0.999771 0.021382 -291.750854
   -0.047076 -0.021359 0.998663 -1871.334229
   0.000000 0.000000 0.000000 1.000000
  ]
  
  tras = Tinv*mano'
  
  hold("on");
  xlabel("X");
  ylabel("Y");
  zlabel("Z");
  
  plot3(p(:,1), p(:,2), p(:,3), 'r*-');
  plot3(tras(1), tras(2), tras(3), 'bo');
  
  hold("off");
  pause;
  </code></pre>