="code">x</code>.
   If <code class="code">x</code> equals <code class="code">y</code>, the function returns <code class="code">y</code>.  If <code class="code">x</code> or <code class="code">y</code> is
   <code class="code">nan</code>, a <code class="code">nan</code> is returned.
   Note that <code class="code">next_after&nbsp;max_float&nbsp;infinity&nbsp;=&nbsp;infinity</code> and that
   <code class="code">next_after&nbsp;0.&nbsp;infinity</code> is the smallest denormalized positive number.
   If <code 