title: What is the result of comparing a number with NaN?
body: <p>Consider for example</p>
  
  <pre><code>bool fun (double a, double b) {
      return a &lt; b;
  }
  </code></pre>
  
  <p>What will <code>fun</code> return if any of the arguments are NaN? Is this undefined / implementation defined behavior?</p>
  
  <p>What happens with the other relational operators and the equality operators?</p>