title: PHP. result of the subtraction of two floating point numbers
body: <p>For example...</p>
  
  <pre><code>$aa = 10694994.89;
  $bb = 10696193.86;
  $ab = $aa - $bb;
  // result is:-1198.9699999988 not the -1198,97
  </code></pre>
  
  <p>But in this exampe:</p>
  
  <pre><code>$cc = 0.89;
  $dd = 0.86;
  $cd = $cc - $dd;
  //Result is: 0.03
  </code></pre>
  
  <p>Why the difference in to examples?  Lacks precision?</p>