PHPOffice / PhpSpreadsheet

     *

     * @return float

     */

    public static function DISC($settlement, $maturity, $price, $redemption, $basis = 0)

    {

        $settlement = Functions::flattenSingleValue($settlement);

        $maturity = Functions::flattenSingleValue($maturity);

        $price = Functions::flattenSingleValue($price);

        $redemption = Functions::flattenSingleValue($redemption);

        $basis = Functions::flattenSingleValue($basis);

        //    Validate

        if ((is_numeric($price)) && (is_numeric($redemption)) && (is_numeric($basis))) {

            $price = (float) $price;

            $redemption = (float) $redemption;

            $basis = (int) $basis;

            if (($price <= 0) || ($redemption <= 0)) {

                return Functions::NAN();

            }

            $daysBetweenSettlementAndMaturity = DateTime::YEARFRAC($settlement, $maturity, $basis);

            if (!is_numeric($daysBetweenSettlementAndMaturity)) {

                //    return date error

                return $daysBetweenSettlementAndMaturity;

            }

            return (1 - $price / $redemption) / $daysBetweenSettlementAndMaturity;

        }

        return Functions::VALUE();

    }

    /**

     * DOLLARDE.

     *

     * @return float

     */

    public static function INTRATE($settlement, $maturity, $investment, $redemption, $basis = 0)

    {

        $settlement = Functions::flattenSingleValue($settlement);

        $maturity = Functions::flattenSingleValue($maturity);

        $investment = Functions::flattenSingleValue($investment);

        $redemption = Functions::flattenSingleValue($redemption);

        $basis = Functions::flattenSingleValue($basis);

        //    Validate

        if ((is_numeric($investment)) && (is_numeric($redemption)) && (is_numeric($basis))) {

            $investment = (float) $investment;

            $redemption = (float) $redemption;

            $basis = (int) $basis;

            if (($investment <= 0) || ($redemption <= 0)) {

                return Functions::NAN();

            }

            $daysBetweenSettlementAndMaturity = DateTime::YEARFRAC($settlement, $maturity, $basis);

            if (!is_numeric($daysBetweenSettlementAndMaturity)) {

                //    return date error

                return $daysBetweenSettlementAndMaturity;

            }

            return (($redemption / $investment) - 1) / ($daysBetweenSettlementAndMaturity);

        }

        return Functions::VALUE();

    }

    /**

     * IPMT.