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

Poisson.php in TablePress – Tables in WordPress made easy 3.4, at libraries/vendor/PhpSpreadsheet/Calculation/Statistical/Distributions/Poisson.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	use TablePress\PhpOffice\PhpSpreadsheet\Calculation\MathTrig;
9
10	class Poisson
11	{
12	use ArrayEnabled;
13
14	/**
15	* POISSON.
16	*
17	* Returns the Poisson distribution. A common application of the Poisson distribution
18	* is predicting the number of events over a specific time, such as the number of
19	* cars arriving at a toll plaza in 1 minute.
20	*
21	* @param mixed $value Float value for which we want the probability
22	* Or can be an array of values
23	* @param mixed $mean Mean value as a float
24	* Or can be an array of values
25	* @param mixed $cumulative Boolean value indicating if we want the cdf (true) or the pdf (false)
26	* Or can be an array of values
27	*
28	* @return array<mixed>\|float\|string The result, or a string containing an error
29	* If an array of numbers is passed as an argument, then the returned result will also be an array
30	* with the same dimensions
31	*/
32	public static function distribution($value, $mean, $cumulative)
33	{
34	if (is_array($value) \|\| is_array($mean) \|\| is_array($cumulative)) {
35	return self::evaluateArrayArguments([self::class, __FUNCTION__], $value, $mean, $cumulative);
36	}
37
38	try {
39	$value = DistributionValidations::validateFloat($value);
40	$mean = DistributionValidations::validateFloat($mean);
41	$cumulative = DistributionValidations::validateBool($cumulative);
42	} catch (Exception $e) {
43	return $e->getMessage();
44	}
45
46	if (($value < 0) \|\| ($mean < 0)) {
47	return ExcelError::NAN();
48	}
49
50	if ($cumulative) {
51	$summer = 0;
52	$floor = floor($value);
53	for ($i = 0; $i <= $floor; ++$i) {
54	/** @var float $fact */
55	$fact = MathTrig\Factorial::fact($i);
56	$summer += $mean ** $i / $fact;
57	}
58
59	return exp(0 - $mean) * $summer;
60	}
61	/** @var float $fact */
62	$fact = MathTrig\Factorial::fact($value);
63
64	return (exp(0 - $mean) * $mean ** $value) / $fact;
65	}
66	}
67