code: public static function DOLLARDE($fractional_dollar = null, $fraction = 0)
      {
          $fractional_dollar = Functions::flattenSingleValue($fractional_dollar);
          $fraction = (int) Functions::flattenSingleValue($fraction);
  
          // Validate parameters
          if ($fractional_dollar === null || $fraction < 0) {
              return Functions::NAN();
          }
          if ($fraction == 0) {
              return Functions::DIV0();
          }
  
          $dollars = floor($fractional_dollar);
          $cents = fmod($fractional_dollar, 1);
          $cents /= $fraction;
          $cents *= pow(10, ceil(log10($fraction)));
  
          return $dollars + $cents;
      }
docs: DOLLARDE.
  
  Converts a dollar price expressed as an integer part and a fraction
  part into a dollar price expressed as a decimal number.
  Fractional dollar numbers are sometimes used for security prices.
  
  Excel Function:
  DOLLARDE(fractional_dollar,fraction)
  
  @category Financial Functions
  
  @param float $fractional_dollar Fractional Dollar
  @param int $fraction Fraction
  
  @return float