<?php
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namespace PhpOffice\PhpSpreadsheet\Calculation\Engineering;
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use PhpOffice\PhpSpreadsheet\Calculation\ArrayEnabled;
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use PhpOffice\PhpSpreadsheet\Calculation\Exception;
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use PhpOffice\PhpSpreadsheet\Calculation\Information\ExcelError;
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class BesselY
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{
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use ArrayEnabled;
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/**
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* BESSELY.
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*
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* Returns the Bessel function, which is also called the Weber function or the Neumann function.
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*
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* Excel Function:
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* BESSELY(x,ord)
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*
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* @param mixed $x A float value at which to evaluate the function.
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* If x is nonnumeric, BESSELY returns the #VALUE! error value.
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* Or can be an array of values
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* @param mixed $ord The integer order of the Bessel function.
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* If ord is not an integer, it is truncated.
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* If $ord is nonnumeric, BESSELY returns the #VALUE! error value.
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* If $ord < 0, BESSELY returns the #NUM! error value.
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* Or can be an array of values
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*
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* @return array|float|string Result, or a string containing an error
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* If an array of numbers is passed as an argument, then the returned result will also be an array
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* with the same dimensions
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*/
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public static function BESSELY(mixed $x, mixed $ord): array|string|float
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{
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if (is_array($x) || is_array($ord)) {
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return self::evaluateArrayArguments([self::class, __FUNCTION__], $x, $ord);
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}
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try {
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$x = EngineeringValidations::validateFloat($x);
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$ord = EngineeringValidations::validateInt($ord);
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} catch (Exception $e) {
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return $e->getMessage();
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}
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if (($ord < 0) || ($x <= 0.0)) {
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return ExcelError::NAN();
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}
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$fBy = self::calculate($x, $ord);
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return (is_nan($fBy)) ? ExcelError::NAN() : $fBy;
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}
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private static function calculate(float $x, int $ord): float
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{
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return match ($ord) {
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0 => self::besselY0($x),
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1 => self::besselY1($x),
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default => self::besselY2($x, $ord),
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};
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}
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/**
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* Mollify Phpstan.
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*
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* @codeCoverageIgnore
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*/
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private static function callBesselJ(float $x, int $ord): float
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{
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$rslt = BesselJ::BESSELJ($x, $ord);
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if (!is_float($rslt)) {
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throw new Exception('Unexpected array or string');
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}
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return $rslt;
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}
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private static function besselY0(float $x): float
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{
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if ($x < 8.0) {
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$y = ($x * $x);
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$ans1 = -2957821389.0 + $y * (7062834065.0 + $y * (-512359803.6 + $y * (10879881.29 + $y
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* (-86327.92757 + $y * 228.4622733))));
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$ans2 = 40076544269.0 + $y * (745249964.8 + $y * (7189466.438 + $y
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* (47447.26470 + $y * (226.1030244 + $y))));
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return $ans1 / $ans2 + 0.636619772 * self::callBesselJ($x, 0) * log($x);
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}
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$z = 8.0 / $x;
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$y = ($z * $z);
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$xx = $x - 0.785398164;
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$ans1 = 1 + $y * (-0.1098628627e-2 + $y * (0.2734510407e-4 + $y * (-0.2073370639e-5 + $y * 0.2093887211e-6)));
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$ans2 = -0.1562499995e-1 + $y * (0.1430488765e-3 + $y * (-0.6911147651e-5 + $y * (0.7621095161e-6 + $y
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* (-0.934945152e-7))));
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return sqrt(0.636619772 / $x) * (sin($xx) * $ans1 + $z * cos($xx) * $ans2);
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}
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private static function besselY1(float $x): float
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{
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if ($x < 8.0) {
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$y = ($x * $x);
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$ans1 = $x * (-0.4900604943e13 + $y * (0.1275274390e13 + $y * (-0.5153438139e11 + $y
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* (0.7349264551e9 + $y * (-0.4237922726e7 + $y * 0.8511937935e4)))));
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$ans2 = 0.2499580570e14 + $y * (0.4244419664e12 + $y * (0.3733650367e10 + $y * (0.2245904002e8 + $y
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* (0.1020426050e6 + $y * (0.3549632885e3 + $y)))));
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return ($ans1 / $ans2) + 0.636619772 * (self::callBesselJ($x, 1) * log($x) - 1 / $x);
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}
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$z = 8.0 / $x;
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$y = $z * $z;
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$xx = $x - 2.356194491;
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$ans1 = 1.0 + $y * (0.183105e-2 + $y * (-0.3516396496e-4 + $y * (0.2457520174e-5 + $y * (-0.240337019e-6))));
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$ans2 = 0.04687499995 + $y * (-0.2002690873e-3 + $y * (0.8449199096e-5 + $y
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* (-0.88228987e-6 + $y * 0.105787412e-6)));
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return sqrt(0.636619772 / $x) * (sin($xx) * $ans1 + $z * cos($xx) * $ans2);
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}
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private static function besselY2(float $x, int $ord): float
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{
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$fTox = 2.0 / $x;
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$fBym = self::besselY0($x);
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$fBy = self::besselY1($x);
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for ($n = 1; $n < $ord; ++$n) {
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$fByp = $n * $fTox * $fBy - $fBym;
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$fBym = $fBy;
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$fBy = $fByp;
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}
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return $fBy;
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}
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}
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