title: How to convert List<Double> to Byte[] in C#
body: <p>Convertion from Double[] src to Byte[] dst
  can be efficiently done in C# by fixed pointers:</p>
  
  <pre><code>fixed( Double* pSrc = src)
  {
    fixed( Byte* pDst = dst)
    {
      Byte* ps = (Byte*)pSrc;
      for (int i=0; i &lt; dstLength; i++)
      {
        *(pDst + i) = *(ps +i);
      }
    }
  }
  </code></pre>
  
  <p>How can I do the same for List src ?
  I.e. how can I get fixed pointer to array Double[]
  included in List ?
  Thanks.</p>