title: Find the minimum of "y=x*x" using genetic algorithm in Matlab
body: <p>Would somebody help me please in this question. I'm new in Matlab... And it's a bit hard for me to understand how to create and use genetic algorithm in Matlab.
   If anybody could help to write some very simple code for searching minimum/maximum of specified function.
   I read that the gatool should be used for that... but I can't understand the examples of Matlab help network. I'm doing the next steps:</p>
  
  <ol>
  <li><p>In text editor I'm typing the next:</p>
  
  <pre><code>function y= parabola(x)
      y=x*x;
  end
  </code></pre></li>
  <li><p>Then I'm launching the <code>GATOOL</code> and specifying this function like <code>@parabola</code></p></li>
  <li>Setting the number of variables (equals 2)</li>
  <li><code>Initial range = [-10;10]</code>.</li>
  <li><p>The other parameters are set as Default</p>
  
  <p>When I press <code>Start</code> Button I see a result: </p>
  
  <blockquote>
    <p>Error in fitnessfcn: Input argument "x" is undefined.</p>
  </blockquote></li>
  </ol>