<p>
    This code checks to see if a floating point value is equal to the special
	Not A Number value (e.g., <code>if (x == Double.NaN)</code>). However,
	because of the special semantics of <code>NaN</code>, no value
	is equal to <code>Nan</code>, including <code>NaN</code>. Thus,
	<code>x == Double.NaN</code> always evaluates to false.

	To check to see if a value contained in <code>x</code>
	is the special Not A Number value, use 
	<code>Double.isNaN(x)</code> (or <code>Float.isNaN(x)</code> if
	<code>x</code> is floating point precision).
    </p>