Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Calculation/Financial.php
public static function YIELDDISC($settlement, $maturity, $price, $redemption, $basis = 0)
    {
        $settlement = Functions::flattenSingleValue($settlement);
        $maturity = Functions::flattenSingleValue($maturity);
        $price = Functions::flattenSingleValue($price);
        $redemption = Functions::flattenSingleValue($redemption);
        $basis = (int) Functions::flattenSingleValue($basis);

        //    Validate
        if (is_numeric($price) && is_numeric($redemption)) {
            if (($price <= 0) || ($redemption <= 0)) {
                return Functions::NAN();
            }
            $daysPerYear = self::daysPerYear(DateTime::YEAR($settlement), $basis);
            if (!is_numeric($daysPerYear)) {
                return $daysPerYear;
            }
            $daysBetweenSettlementAndMaturity = DateTime::YEARFRAC($settlement, $maturity, $basis);
            if (!is_numeric($daysBetweenSettlementAndMaturity)) {
                //    return date error
                return $daysBetweenSettlementAndMaturity;
            }
            $daysBetweenSettlementAndMaturity *= $daysPerYear;

            return (($redemption - $price) / $price) * ($daysPerYear / $daysBetweenSettlementAndMaturity);
        }

        return Functions::VALUE();
    }
public static function YIELDDISC($settlement, $maturity, $price, $redemption, $basis = 0)
    {
        $settlement = Functions::flattenSingleValue($settlement);
        $maturity = Functions::flattenSingleValue($maturity);
        $price = Functions::flattenSingleValue($price);
        $redemption = Functions::flattenSingleValue($redemption);
        $basis = (int) Functions::flattenSingleValue($basis);

        //    Validate
        if (is_numeric($price) && is_numeric($redemption)) {
            if (($price <= 0) || ($redemption <= 0)) {
                return Functions::NAN();
            }
            $daysPerYear = self::daysPerYear(DateTime::YEAR($settlement), $basis);
            if (!is_numeric($daysPerYear)) {
                return $daysPerYear;
            }
            $daysBetweenSettlementAndMaturity = DateTime::YEARFRAC($settlement, $maturity, $basis);
            if (!is_numeric($daysBetweenSettlementAndMaturity)) {
                //    return date error
                return $daysBetweenSettlementAndMaturity;
            }
            $daysBetweenSettlementAndMaturity *= $daysPerYear;

            return (($redemption - $price) / $price) * ($daysPerYear / $daysBetweenSettlementAndMaturity);
        }

        return Functions::VALUE();
    }
YIELDDISC.

Returns the annual yield of a security that pays interest at maturity.

@param mixed $settlement The security's settlement date.
The security's settlement date is the date after the issue date when the security is traded to the buyer.
@param mixed $maturity The security's maturity date.
The maturity date is the date when the security expires.
@param int $price The security's price per $100 face value
@param int $redemption The security's redemption value per $100 face value
@param int $basis The type of day count to use.
0 or omitted    US (NASD) 30/360
1                Actual/actual
2                Actual/360
3                Actual/365
4                European 30/360

@return float