code: public static function SUMSQ(...$args)
      {
          $returnValue = 0;
  
          // Loop through arguments
          foreach (Functions::flattenArray($args) as $arg) {
              // Is it a numeric value?
              if ((is_numeric($arg)) && (!is_string($arg))) {
                  $returnValue += ($arg * $arg);
              }
          }
  
          return $returnValue;
      }
docs: SUMSQ.
  
  SUMSQ returns the sum of the squares of the arguments
  
  Excel Function:
  SUMSQ(value1[,value2[, ...]])
  
  @category Mathematical and Trigonometric Functions
  
  @param mixed ...$args Data values
  
  @return float