code: public static function MOD($a = 1, $b = 1)
      {
          $a = (float) Functions::flattenSingleValue($a);
          $b = (float) Functions::flattenSingleValue($b);
  
          if ($b == 0.0) {
              return Functions::DIV0();
          } elseif (($a < 0.0) && ($b > 0.0)) {
              return $b - fmod(abs($a), $b);
          } elseif (($a > 0.0) && ($b < 0.0)) {
              return $b + fmod($a, abs($b));
          }
  
          return fmod($a, $b);
      }
docs: MOD.
  
  @param int $a Dividend
  @param int $b Divisor
  
  @return int Remainder