title: Objective-C - float checking for nan
body: <p>I have a variable <code>float slope</code> that sometimes will have a value of <code>nan</code> when printed out since a division by<code> 0</code> sometimes happens.</p>
  <p>I am trying to do an if-else for when that happens. How can I do that? <code>if (slope == nan)</code> doesn't seem to work.</p>