Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Calculation/Financial.php
public static function FV($rate = 0, $nper = 0, $pmt = 0, $pv = 0, $type = 0)
    {
        $rate = Functions::flattenSingleValue($rate);
        $nper = Functions::flattenSingleValue($nper);
        $pmt = Functions::flattenSingleValue($pmt);
        $pv = Functions::flattenSingleValue($pv);
        $type = Functions::flattenSingleValue($type);

        // Validate parameters
        if ($type != 0 && $type != 1) {
            return Functions::NAN();
        }

        // Calculate
        if ($rate !== null && $rate != 0) {
            return -$pv * pow(1 + $rate, $nper) - $pmt * (1 + $rate * $type) * (pow(1 + $rate, $nper) - 1) / $rate;
        }

        return -$pv - $pmt * $nper;
    }
public static function FV($rate = 0, $nper = 0, $pmt = 0, $pv = 0, $type = 0)
    {
        $rate = Functions::flattenSingleValue($rate);
        $nper = Functions::flattenSingleValue($nper);
        $pmt = Functions::flattenSingleValue($pmt);
        $pv = Functions::flattenSingleValue($pv);
        $type = Functions::flattenSingleValue($type);

        // Validate parameters
        if ($type != 0 && $type != 1) {
            return Functions::NAN();
        }

        // Calculate
        if ($rate !== null && $rate != 0) {
            return -$pv * pow(1 + $rate, $nper) - $pmt * (1 + $rate * $type) * (pow(1 + $rate, $nper) - 1) / $rate;
        }

        return -$pv - $pmt * $nper;
    }
FV.

Returns the Future Value of a cash flow with constant payments and interest rate (annuities).

Excel Function:
FV(rate,nper,pmt[,pv[,type]])

@category Financial Functions

@param float $rate The interest rate per period
@param int $nper Total number of payment periods in an annuity
@param float $pmt The payment made each period: it cannot change over the
life of the annuity. Typically, pmt contains principal
and interest but no other fees or taxes.
@param float $pv present Value, or the lump-sum amount that a series of
future payments is worth right now
@param int $type A number 0 or 1 and indicates when payments are due:
0 or omitted    At the end of the period.
1                At the beginning of the period.

@return float