title: Octave 3D mesh, data from file
body: <p>I have a big file with 3 columns: density, dimension, value.<br>
  example:</p>
  
  <pre><code>10 0.3 200  
  10 0.4 300  
  20 0.3 250  
  20 0.4 320 
  </code></pre>
  
  <p>I am trying to draw a 3d plot - mesh with <code>mesh()</code> function in octave, like this:  </p>
  
  <pre><code>data = load ("file.txt");   
  mesh(data(:,1), data (:,2), data (:,3));  
  </code></pre>
  
  <p>Problem I have is , I always get error:  </p>
  
  <blockquote>
    <p>rows (z) must be the same as length (y), columns (z) must be the same as length (x). </p>
  </blockquote>
  
  <p>It worked with function <code>plot3()</code>, but I would like a mesh kind of plot.  </p>