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<?php
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namespace PhpOffice\PhpSpreadsheet\Calculation\Statistical;
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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\Functions;
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use PhpOffice\PhpSpreadsheet\Calculation\Information\ExcelError;
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class Confidence
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{
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use ArrayEnabled;
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/**
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* CONFIDENCE.
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*
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* Returns the confidence interval for a population mean
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*
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* @param mixed $alpha As a float
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* Or can be an array of values
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* @param mixed $stdDev Standard Deviation as a float
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* Or can be an array of values
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* @param mixed $size As an integer
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* Or can be an array of values
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*
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* @return array|float|string 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 CONFIDENCE(mixed $alpha, mixed $stdDev, mixed $size)
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{
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if (is_array($alpha) || is_array($stdDev) || is_array($size)) {
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return self::evaluateArrayArguments([self::class, __FUNCTION__], $alpha, $stdDev, $size);
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}
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try {
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$alpha = StatisticalValidations::validateFloat($alpha);
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$stdDev = StatisticalValidations::validateFloat($stdDev);
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$size = StatisticalValidations::validateInt($size);
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} catch (Exception $e) {
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return $e->getMessage();
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}
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if (($alpha <= 0) || ($alpha >= 1) || ($stdDev <= 0) || ($size < 1)) {
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return ExcelError::NAN();
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}
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/** @var float $temp */
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$temp = Distributions\StandardNormal::inverse(1 - $alpha / 2);
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return Functions::scalar($temp * $stdDev / sqrt($size));
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}
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}
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