title: How to calculate bollinger bands from array in php
body: <p>I want to calculate bollinger bands using php with my array of data. </p>
  
  <p>I have tried using <code>trader_bbands</code> <a href="http://php.net/manual/en/function.trader-bbands.php" rel="nofollow noreferrer">here</a> but I don't understand the parameter that I should put in especially the <code>$nbDevUp</code>, <code>$nbDecDn</code>, and <code>$mAType</code>.  Then I wondered how to calculate it manually using php, maybe using queue to calculate the middle band or something?</p>
  
  <p>Can anyone help me to understand <code>trader_bbands</code>?  I've found <a href="https://stackoverflow.com/questions/40866649/what-is-the-meaning-of-the-values-returned-from-trader-bbands">this</a> but it asks about the return value not the parameter of it.</p>