tablepress / libraries / vendor / PhpSpreadsheet / Calculation / Statistical / Distributions / Weibull.php

Weibull.php in TablePress – Tables in WordPress made easy 3.4, at libraries/vendor/PhpSpreadsheet/Calculation/Statistical/Distributions/Weibull.php

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1	<?php
2
3	namespace TablePress\PhpOffice\PhpSpreadsheet\Calculation\Statistical\Distributions;
4
5	use TablePress\PhpOffice\PhpSpreadsheet\Calculation\ArrayEnabled;
6	use TablePress\PhpOffice\PhpSpreadsheet\Calculation\Exception;
7	use TablePress\PhpOffice\PhpSpreadsheet\Calculation\Information\ExcelError;
8
9	class Weibull
10	{
11	use ArrayEnabled;
12
13	/**
14	* WEIBULL.
15	*
16	* Returns the Weibull distribution. Use this distribution in reliability
17	* analysis, such as calculating a device's mean time to failure.
18	*
19	* @param mixed $value Float value for the distribution
20	* Or can be an array of values
21	* @param mixed $alpha Float alpha Parameter
22	* Or can be an array of values
23	* @param mixed $beta Float beta Parameter
24	* Or can be an array of values
25	* @param mixed $cumulative Boolean value indicating if we want the cdf (true) or the pdf (false)
26	* Or can be an array of values
27	*
28	* @return array<mixed>\|float\|string (string if result is an error)
29	* If an array of numbers is passed as an argument, then the returned result will also be an array
30	* with the same dimensions
31	*/
32	public static function distribution($value, $alpha, $beta, $cumulative)
33	{
34	if (is_array($value) \|\| is_array($alpha) \|\| is_array($beta) \|\| is_array($cumulative)) {
35	return self::evaluateArrayArguments([self::class, __FUNCTION__], $value, $alpha, $beta, $cumulative);
36	}
37
38	try {
39	$value = DistributionValidations::validateFloat($value);
40	$alpha = DistributionValidations::validateFloat($alpha);
41	$beta = DistributionValidations::validateFloat($beta);
42	$cumulative = DistributionValidations::validateBool($cumulative);
43	} catch (Exception $e) {
44	return $e->getMessage();
45	}
46
47	if (($value < 0) \|\| ($alpha <= 0) \|\| ($beta <= 0)) {
48	return ExcelError::NAN();
49	}
50
51	if ($cumulative) {
52	return 1 - exp(0 - ($value / $beta) ** $alpha);
53	}
54
55	return ($alpha / $beta ** $alpha) * $value ** ($alpha - 1) * exp(0 - ($value / $beta) ** $alpha);
56	}
57	}
58