title: What does ordered / unordered comparison mean?
body: <p>Looking at the SSE operators</p>
  
  <pre><code>CMPORDPS - ordered compare packed singles
  CMPUNORDPS - unordered compare packed singles
  </code></pre>
  
  <p>What do ordered and unordered mean? I looked for equivalent instructions in the x86 instruction set, and it only seems to have unordered (FUCOM).</p>