Fisher.php

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<?php

namespace PhpOffice\PhpSpreadsheet\Calculation\Statistical\Distributions;

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

class Fisher
{
    public static function distribution($value)
    {
        $value = Functions::flattenSingleValue($value);

        try {
            DistributionValidations::validateFloat($value);
        } catch (Exception $e) {
            return $e->getMessage();
        }

        if (($value <= -1) || ($value >= 1)) {
            return Functions::NAN();
        }

        return 0.5 * log((1 + $value) / (1 - $value));
    }

    public static function inverse($probability)
    {
        $probability = Functions::flattenSingleValue($probability);

        try {
            DistributionValidations::validateFloat($probability);
        } catch (Exception $e) {
            return $e->getMessage();
        }

        return (exp(2 * $probability) - 1) / (exp(2 * $probability) + 1);
    }
}