Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Calculation/Financial.php
public static function NOMINAL($effect_rate = 0, $npery = 0)
    {
        $effect_rate = Functions::flattenSingleValue($effect_rate);
        $npery = (int) Functions::flattenSingleValue($npery);

        // Validate parameters
        if ($effect_rate <= 0 || $npery < 1) {
            return Functions::NAN();
        }

        // Calculate
        return $npery * (pow($effect_rate + 1, 1 / $npery) - 1);
    }
public static function NOMINAL($effect_rate = 0, $npery = 0)
    {
        $effect_rate = Functions::flattenSingleValue($effect_rate);
        $npery = (int) Functions::flattenSingleValue($npery);

        // Validate parameters
        if ($effect_rate <= 0 || $npery < 1) {
            return Functions::NAN();
        }

        // Calculate
        return $npery * (pow($effect_rate + 1, 1 / $npery) - 1);
    }
NOMINAL.

Returns the nominal interest rate given the effective rate and the number of compounding payments per year.

@param float $effect_rate Effective interest rate
@param int $npery Number of compounding payments per year

@return float