title: OCaml, PLplot, get rid of the prompt
body: <p>When I use the "native" PLplot in OCaml (i.e. just calling plinit ()), I have the following output in the terminal :</p>
  
  <pre><code>Plotting Options:
   &lt; 1&gt; ps         PostScript File (monochrome)
   &lt; 2&gt; psc        PostScript File (color)
   &lt; 3&gt; xfig       Fig file
   &lt; 4&gt; null       Null device
   &lt; 5&gt; mem        User-supplied memory device
   &lt; 6&gt; wxwidgets  wxWidgets Driver
   &lt; 7&gt; svg        Scalable Vector Graphics (SVG 1.1)
   &lt; 8&gt; bmpqt      Qt Windows bitmap driver
   &lt; 9&gt; jpgqt      Qt jpg driver
   &lt;10&gt; pngqt      Qt png driver
   &lt;11&gt; ppmqt      Qt ppm driver
   &lt;12&gt; tiffqt     Qt tiff driver
   &lt;13&gt; svgqt      Qt SVG driver
   &lt;14&gt; qtwidget   Qt Widget
   &lt;15&gt; epsqt      Qt EPS driver
   &lt;16&gt; pdfqt      Qt PDF driver
   &lt;17&gt; extqt      External Qt driver
   &lt;18&gt; memqt      Memory Qt driver
  </code></pre>
  
  <p>However, when I use :</p>
  
  <pre><code>module P = Plot
  
  p = P.init (0., 0.) 
      (max_length, max_length) 
      `greedy 
      (`svg `core)
      ~filename:("myfile.svg");
  </code></pre>
  
  <p>I can output my graph to an external file. </p>
  
  <p>The problem is that most of the three dimensional plots cannot be called from the "module P". I have a large number of graphs to generate and answering the prompts becomes the bottleneck...</p>
  
  <p>Is there a way to have PLplot output the graphs into a file directly ?</p>