Ceiling / round / floor in prolog
<p>When I try to execute the following query with prolog swi  version 7.2.3,</p>

<p><code>ceiling(1.5)</code> it says,</p>

<pre><code> ERROR: toplevel: Undefined procedure: ceiling/1 (DWIM could not correct goal.)
</code></pre>

<p>How do I get the "ceiling" working for this case? </p>