Code Coverage for /var/www/html/dev/src/phpOMS/Math/Solver/Root/Bisection.php

1	<?php
2	/**
3	* Jingga
4	*
5	* PHP Version 8.1
6	*
7	* @package phpOMS\Math\Solver\Root
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\Solver\Root;
16
17	/**
18	* Find the root of a function.
19	*
20	* @package phpOMS\Math\Solver\Root
21	* @license OMS License 2.0
22	* @link https://jingga.app
23	* @since 1.0.0
24	*/
25	final class Bisection
26	{
27	/**
28	* Epsilon for float comparison.
29	*
30	* @var float
31	* @since 1.0.0
32	*/
33	public const EPSILON = 1e-6;
34
35	/**
36	* Perform bisection to find the root of a function
37	*
38	* Iteratively searches for root between two points on the x-axis
39	*
40	* @param Callable $func Function defintion
41	* @param float $a Start value
42	* @param float $b End value
43	* @param int $maxIterations Maximum amount of iterations
44	*
45	* @throws \Exception
46	*
47	* @return float
48	*
49	* @since 1.0.0
50	*/
51	public static function root(callable $func, float $a, float $b, int $maxIterations = 100) : float
52	{
53	if ($func($a) * $func($b) >= 0) {
54	throw new \Exception("Function values at endpoints must have opposite signs.");
55	}
56
57	$iteration = 0;
58	while (($b - $a) / 2 > self::EPSILON && $iteration < $maxIterations) {
59	$c = ($a + $b) / 2;
60
61	$y = $func($c);
62
63	if ($y === 0.0) {
64	return $c;
65	}
66
67	if ($y * $func($a) < 0) {
68	$b = $c;
69	} else {
70	$a = $c;
71	}
72
73	++$iteration;
74	}
75
76	return ($a + $b) / 2;
77	}
78	}