code: public static function VARA(...$args)
      {
          $returnValue = Functions::DIV0();
  
          $summerA = $summerB = 0;
  
          // Loop through arguments
          $aArgs = Functions::flattenArrayIndexed($args);
          $aCount = 0;
          foreach ($aArgs as $k => $arg) {
              if ((is_string($arg)) &&
                  (Functions::isValue($k))) {
                  return Functions::VALUE();
              } elseif ((is_string($arg)) &&
                  (!Functions::isMatrixValue($k))) {
              } else {
                  // Is it a numeric value?
                  if ((is_numeric($arg)) || (is_bool($arg)) || ((is_string($arg) & ($arg != '')))) {
                      if (is_bool($arg)) {
                          $arg = (int) $arg;
                      } elseif (is_string($arg)) {
                          $arg = 0;
                      }
                      $summerA += ($arg * $arg);
                      $summerB += $arg;
                      ++$aCount;
                  }
              }
          }
  
          if ($aCount > 1) {
              $summerA *= $aCount;
              $summerB *= $summerB;
              $returnValue = ($summerA - $summerB) / ($aCount * ($aCount - 1));
          }
  
          return $returnValue;
      }
docs: VARA.
  
  Estimates variance based on a sample, including numbers, text, and logical values
  
  Excel Function:
  VARA(value1[,value2[, ...]])
  
  @category Statistical Functions
  
  @param mixed ...$args Data values
  
  @return float