title: Is DBL_MIN the smallest positive double?
body: <p><strong>Q:</strong> Is DBL_MIN the smallest positive double?</p>
  <p>The code below seems to anwser this question with no. But if this is true, how is DBL_MIN the defined and what is its use or purpose.</p>
  <p>Platform: Windows7 &amp; Visual Studio 2013</p>
  <pre><code>double next_to_zero = std::nextafter(0.0,DBL_MIN);
  bool b =  DBL_MIN &lt;= next_to_zero;
  std::cout &lt;&lt; std::boolalpha 
            &lt;&lt; &quot;is dbl_min the smallest representable double? &quot;
            &lt;&lt; b &lt;&lt; '\n';
  
  std::cout &lt;&lt; std::setprecision(56)
            &lt;&lt; &quot;dbl_min = &quot; &lt;&lt; DBL_MIN &lt;&lt; '\n'
            &lt;&lt; &quot;next to zero = &quot; &lt;&lt; next_to_zero;
  </code></pre>
  <p>outputs:</p>
  <blockquote>
  <p>is dbl_min the smallest representable double? false</p>
  <p>dbl_min = 2.2250738585072013830902327173324040642192159804623318306e-308</p>
  <p>next to zero = 4.9406564584124654417656879286822137236505980261432476443e-324</p>
  </blockquote>