title: How to check if a number is a positive natural number?
body: <p>I'd appreciate any idea on how to do it, so we can compare them with each other.</p>
  
  <p>Here is one to start out with:</p>
  
  <pre><code>is.natural &lt;- function(x)
  {
       x&gt;0 &amp;&amp; identical(round(x), x)
  }
  </code></pre>