# tablepress/3.4/libraries/vendor/PhpSpreadsheet/Calculation/Engineering/BesselY.php

TablePress – Tables in WordPress made easy, version 3.4. 141 lines.

- Page: https://pluginprobe.com/plugins/tablepress/3.4/code/libraries/vendor/PhpSpreadsheet/Calculation/Engineering/BesselY.php
- Raw: https://pluginprobe.com/plugins/tablepress/3.4/raw/libraries/vendor/PhpSpreadsheet/Calculation/Engineering/BesselY.php
- Modified: 2025-08-26T04:06:14+00:00

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```php
<?php

namespace TablePress\PhpOffice\PhpSpreadsheet\Calculation\Engineering;

use TablePress\PhpOffice\PhpSpreadsheet\Calculation\ArrayEnabled;
use TablePress\PhpOffice\PhpSpreadsheet\Calculation\Exception;
use TablePress\PhpOffice\PhpSpreadsheet\Calculation\Information\ExcelError;

class BesselY
{
	use ArrayEnabled;

	/**
	 * BESSELY.
	 *
	 * Returns the Bessel function, which is also called the Weber function or the Neumann function.
	 *
	 *    Excel Function:
	 *        BESSELY(x,ord)
	 *
	 * @param mixed $x A float value at which to evaluate the function.
	 *                   If x is nonnumeric, BESSELY returns the #VALUE! error value.
	 *                      Or can be an array of values
	 * @param mixed $ord The integer order of the Bessel function.
	 *                       If ord is not an integer, it is truncated.
	 *                       If $ord is nonnumeric, BESSELY returns the #VALUE! error value.
	 *                       If $ord < 0, BESSELY returns the #NUM! error value.
	 *                      Or can be an array of values
	 *
	 * @return array<mixed>|float|string Result, or a string containing an error
	 *         If an array of numbers is passed as an argument, then the returned result will also be an array
	 *            with the same dimensions
	 */
	public static function BESSELY($x, $ord)
	{
		if (is_array($x) || is_array($ord)) {
			return self::evaluateArrayArguments([self::class, __FUNCTION__], $x, $ord);
		}

		try {
			$x = EngineeringValidations::validateFloat($x);
			$ord = EngineeringValidations::validateInt($ord);
		} catch (Exception $e) {
			return $e->getMessage();
		}

		if (($ord < 0) || ($x <= 0.0)) {
			return ExcelError::NAN();
		}

		$fBy = self::calculate($x, $ord);

		return (is_nan($fBy)) ? ExcelError::NAN() : $fBy;
	}

	private static function calculate(float $x, int $ord): float
	{
		switch ($ord) {
									case 0:
										return self::besselY0($x);
									case 1:
										return self::besselY1($x);
									default:
										return self::besselY2($x, $ord);
								}
	}

	/**
	 * Mollify Phpstan.
	 *
	 * @codeCoverageIgnore
	 */
	private static function callBesselJ(float $x, int $ord): float
	{
		$rslt = BesselJ::BESSELJ($x, $ord);
		if (!is_float($rslt)) {
			throw new Exception('Unexpected array or string');
		}

		return $rslt;
	}

	private static function besselY0(float $x): float
	{
		if ($x < 8.0) {
			$y = ($x * $x);
			$ans1 = -2957821389.0 + $y * (7062834065.0 + $y * (-512359803.6 + $y * (10879881.29 + $y
							* (-86327.92757 + $y * 228.4622733))));
			$ans2 = 40076544269.0 + $y * (745249964.8 + $y * (7189466.438 + $y
						* (47447.26470 + $y * (226.1030244 + $y))));

			return $ans1 / $ans2 + 0.636619772 * self::callBesselJ($x, 0) * log($x);
		}

		$z = 8.0 / $x;
		$y = ($z * $z);
		$xx = $x - 0.785398164;
		$ans1 = 1 + $y * (-0.1098628627e-2 + $y * (0.2734510407e-4 + $y * (-0.2073370639e-5 + $y * 0.2093887211e-6)));
		$ans2 = -0.1562499995e-1 + $y * (0.1430488765e-3 + $y * (-0.6911147651e-5 + $y * (0.7621095161e-6 + $y
						* (-0.934945152e-7))));

		return sqrt(0.636619772 / $x) * (sin($xx) * $ans1 + $z * cos($xx) * $ans2);
	}

	private static function besselY1(float $x): float
	{
		if ($x < 8.0) {
			$y = ($x * $x);
			$ans1 = $x * (-0.4900604943e13 + $y * (0.1275274390e13 + $y * (-0.5153438139e11 + $y
							* (0.7349264551e9 + $y * (-0.4237922726e7 + $y * 0.8511937935e4)))));
			$ans2 = 0.2499580570e14 + $y * (0.4244419664e12 + $y * (0.3733650367e10 + $y * (0.2245904002e8 + $y
							* (0.1020426050e6 + $y * (0.3549632885e3 + $y)))));

			return ($ans1 / $ans2) + 0.636619772 * (self::callBesselJ($x, 1) * log($x) - 1 / $x);
		}

		$z = 8.0 / $x;
		$y = $z * $z;
		$xx = $x - 2.356194491;
		$ans1 = 1.0 + $y * (0.183105e-2 + $y * (-0.3516396496e-4 + $y * (0.2457520174e-5 + $y * (-0.240337019e-6))));
		$ans2 = 0.04687499995 + $y * (-0.2002690873e-3 + $y * (0.8449199096e-5 + $y
					* (-0.88228987e-6 + $y * 0.105787412e-6)));

		return sqrt(0.636619772 / $x) * (sin($xx) * $ans1 + $z * cos($xx) * $ans2);
	}

	private static function besselY2(float $x, int $ord): float
	{
		$fTox = 2.0 / $x;
		$fBym = self::besselY0($x);
		$fBy = self::besselY1($x);
		for ($n = 1; $n < $ord; ++$n) {
			$fByp = $n * $fTox * $fBy - $fBym;
			$fBym = $fBy;
			$fBy = $fByp;
		}

		return $fBy;
	}
}

```