Standardize.php

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<?php

namespace PhpOffice\PhpSpreadsheet\Calculation\Statistical;

use PhpOffice\PhpSpreadsheet\Calculation\Exception;
use PhpOffice\PhpSpreadsheet\Calculation\Functions;

class Standardize extends StatisticalValidations
{
    public static function execute($value, $mean, $stdDev)
    {
        $value = Functions::flattenSingleValue($value);
        $mean = Functions::flattenSingleValue($mean);
        $stdDev = Functions::flattenSingleValue($stdDev);

        try {
            $value = self::validateFloat($value);
            $mean = self::validateFloat($mean);
            $stdDev = self::validateFloat($stdDev);
        } catch (Exception $e) {
            return $e->getMessage();
        }

        if ($stdDev <= 0) {
            return Functions::NAN();
        }

        return ($value - $mean) / $stdDev;
    }
}