Code Coverage for /var/www/html/dev/src/phpOMS/Math/Topology/KernelsND.php

1	<?php
2	/**
3	* Jingga
4	*
5	* PHP Version 8.1
6	*
7	* @package phpOMS\Math\Topology
8	* @copyright Dennis Eichhorn
9	* @license OMS License 2.0
10	* @version 1.0.0
11	* @link https://jingga.app
12	*/
13	declare(strict_types=1);
14
15	namespace phpOMS\Math\Topology;
16
17	use phpOMS\Math\Matrix\IdentityMatrix;
18	use phpOMS\Math\Matrix\Matrix;
19
20	/**
21	* Kernels.
22	*
23	* @package phpOMS\Math\Topology
24	* @license OMS License 2.0
25	* @link https://jingga.app
26	* @since 1.0.0
27	*/
28	final class KernelsND
29	{
30	/**
31	* Constructor
32	*
33	* @since 1.0.0
34	* @codeCoverageIgnore
35	*/
36	private function __construct()
37	{
38	}
39
40	/**
41	* Gaussian kernel
42	*
43	* @param array<float\|int> $distances Distances
44	* @param array<float\|int> $bandwidths Bandwidths
45	*
46	* @return array
47	*
48	* @since 1.0.0
49	*/
50	public static function gaussianKernel(array $distances, array $bandwidths) : array
51	{
52	$dim = \count($bandwidths);
53
54	$bandwithMatrix = Matrix::fromArray($bandwidths);
55	$distnaceMatrix = Matrix::fromArray($distances);
56	$identityMatrix = new IdentityMatrix($dim);
57
58	$cov = $bandwithMatrix->mult($identityMatrix);
59
60	/** @phpstan-ignore-next-line */
61	$exponent = $distnaceMatrix->dot($cov->inverse())->mult($distnaceMatrix)->sum(1)->mult(-0.5);
62
63	return $exponent->exp()->mult((1 / \pow(2 * \M_PI, $dim / 2)) * \pow($cov->det(), 0.5))->matrix;
64	}
65	}