level2">
<h2><span class="header-section-number">3.3</span> Special Values</h2>
<!-- real; not_a_number; () -->
<p></p>
<p><code>real</code> <strong><code>not_a_number</code></strong><code>()</code><br>
Not-a-number, a special non-finite real value returned to signal an
error</p>
<!-- real; positive_infinity; () -->
<p></p>
<p><code>real</code> <strong><code>positive_infinity</code></strong><code>()</code><br>
Positive infinity, a special non-finite real value larger than all
finite numbers</p>
<!-- real; n