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

Exponential.php in TablePress – Tables in WordPress made easy 3.4, at libraries/vendor/PhpSpreadsheet/Calculation/Statistical/Distributions/Exponential.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 Exponential
10	{
11	use ArrayEnabled;
12
13	/**
14	* EXPONDIST.
15	*
16	* Returns the exponential distribution. Use EXPONDIST to model the time between events,
17	* such as how long an automated bank teller takes to deliver cash. For example, you can
18	* use EXPONDIST to determine the probability that the process takes at most 1 minute.
19	*
20	* @param mixed $value Float value for which we want the probability
21	* Or can be an array of values
22	* @param mixed $lambda The parameter value as a float
23	* Or can be an array of values
24	* @param mixed $cumulative Boolean value indicating if we want the cdf (true) or the pdf (false)
25	* Or can be an array of values
26	*
27	* @return array<mixed>\|float\|string If an array of numbers is passed as an argument, then the returned result will also be an array
28	* with the same dimensions
29	*/
30	public static function distribution($value, $lambda, $cumulative)
31	{
32	if (is_array($value) \|\| is_array($lambda) \|\| is_array($cumulative)) {
33	return self::evaluateArrayArguments([self::class, __FUNCTION__], $value, $lambda, $cumulative);
34	}
35
36	try {
37	$value = DistributionValidations::validateFloat($value);
38	$lambda = DistributionValidations::validateFloat($lambda);
39	$cumulative = DistributionValidations::validateBool($cumulative);
40	} catch (Exception $e) {
41	return $e->getMessage();
42	}
43
44	if (($value < 0) \|\| ($lambda < 0)) {
45	return ExcelError::NAN();
46	}
47
48	if ($cumulative === true) {
49	return 1 - exp(0 - $value * $lambda);
50	}
51
52	return $lambda * exp(0 - $value * $lambda);
53	}
54	}
55