title: Convert cell to double
body: <pre><code>&gt;&gt; C = [{1} {2} ; {'@CF'} {2}] 
  C = 
  
  [  1]    [2]
  '@CF'    [2]
  
  
  &gt;&gt; whos C
    Name      Size            Bytes  Class    Attributes
  
    C         2x2               478  cell  
  </code></pre>
  
  <p>How can I convert <code>C</code> into <code>double</code> so that:</p>
  
  <pre><code>&gt;&gt; C
  C = 
  1    2
  NaN  2
  </code></pre>
  
  <p>I've tried <code>str2double(C)</code>.  It returns:</p>
  
  <pre><code>   NaN   NaN
     NaN   NaN
  </code></pre>