title: Using math.isclose function with values close to 0
body: <p>As we know, due to the binary representation of numbers, this expression evaluates to <code>False</code> (at least in Python):</p>
  
  <pre><code>0.2 + 0.4 == 0.6
  </code></pre>
  
  <p>In order to be able to check for equality within numerical errors, the module <code>math</code> offers <code>isclose</code>:</p>
  
  <pre><code>import math
  math.isclose(0.2 + 0.4 , 0.6)
  </code></pre>
  
  <p>This last expression yields <code>True</code> as expected.</p>
  
  <p>Now <strong>why does this following expression is <code>False</code> again?</strong></p>
  
  <pre><code>math.isclose(0.2 + 0.4 - 0.6 , 0.0)
  </code></pre>
  
  <p>It appears that everything compared to <code>0.0</code> is <code>False</code></p>
  
  <pre><code>math.isclose(1.0e-100 , 0.0)
  </code></pre>