PHPOffice / PhpSpreadsheet

     *            accuracy if I can get my head round the mathematics

     *            (as described at) http://home.online.no/~pjacklam/notes/invnorm/

     */

    public static function LOGINV($probability, $mean, $stdDev)

    {

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

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

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

        if ((is_numeric($probability)) && (is_numeric($mean)) && (is_numeric($stdDev))) {

            if (($probability < 0) || ($probability > 1) || ($stdDev <= 0)) {

                return Functions::NAN();

            }

            return exp($mean + $stdDev * self::NORMSINV($probability));

        }

        return Functions::VALUE();

    }

     * @param    float        $stdDev        Standard Deviation

     * @return    float

     */

    public static function NORMINV($probability, $mean, $stdDev)

    {

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

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

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

        if ((is_numeric($probability)) && (is_numeric($mean)) && (is_numeric($stdDev))) {

            if (($probability < 0) || ($probability > 1)) {

                return Functions::NAN();

            }

            if ($stdDev < 0) {

                return Functions::NAN();

            }

            return (self::inverseNcdf($probability) * $stdDev) + $mean;

        }

        return Functions::VALUE();

    }