phpOMS/Math/Functions/Functions.php
Dennis Eichhorn 2ea1d0373d
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inspection fixes
2024-05-17 14:15:52 +00:00

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PHP
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<?php
/**
* Jingga
*
* PHP Version 8.2
*
* @package phpOMS\Math\Functions
* @copyright Dennis Eichhorn
* @license OMS License 2.0
* @version 1.0.0
* @link https://jingga.app
*/
declare(strict_types=1);
namespace phpOMS\Math\Functions;
/**
* Well known functions and helpers class.
*
* @package phpOMS\Math\Functions
* @license OMS License 2.0
* @link https://jingga.app
* @since 1.0.0
*/
final class Functions
{
/**
* Epsilon for float comparison.
*
* @var float
* @since 1.0.0
*/
public const EPSILON = 4.88e-04;
/**
* Constructor.
*
* @since 1.0.0
* @codeCoverageIgnore
*/
private function __construct()
{
}
/**
* Calculate gammar function value.
*
* Example: (7, 2)
*
* @param int $n Factorial upper bound
* @param int $start Factorial starting value
*
* @return int
*
* @since 1.0.0
*/
public static function fact(int $n, int $start = 1) : int
{
$fact = 1;
for ($i = $start; $i < $n + 1; ++$i) {
$fact *= $i;
}
return $fact;
}
/**
* Calculate binomial coefficient
*
* Algorithm optimized for large factorials without the use of big int or string manipulation.
*
* Example: (7, 2)
*
* @param int $n n
* @param int $k k
*
* @return int
*
* @since 1.0.0
*/
public static function binomialCoefficient(int $n, int $k) : int
{
$max = \max([$k, $n - $k]);
$min = \min([$k, $n - $k]);
$fact = 1;
$range = \array_reverse(\range(1, $min));
for ($i = $max + 1; $i < $n + 1; ++$i) {
$div = 1;
foreach ($range as $key => $d) {
if ($i % $d === 0) {
$div = $d;
unset($range[$key]);
break;
}
}
$fact *= $i / $div;
}
$fact2 = 1;
foreach ($range as $d) {
$fact2 *= $d;
}
return (int) ($fact / $fact2);
}
/**
* Calculate ackermann function.
*
* @param int $m m
* @param int $n n
*
* @return int
*
* @since 1.0.0
*/
public static function ackermann(int $m, int $n) : int
{
if ($m === 0) {
return $n + 1;
} elseif ($n === 0) {
return self::ackermann($m - 1, 1);
}
return self::ackermann($m - 1, self::ackermann($m, $n - 1));
}
/**
* Calculate inverse modular.
*
* @param int $a a
* @param int $n Modulo
*
* @return int
*
* @since 1.0.0
*/
public static function invMod(int $a, int $n) : int
{
if ($n < 0) {
$n = -$n;
}
if ($a < 0) {
$a = $n - (-$a % $n);
}
$t = 0;
$nt = 1;
$r = $n;
$nr = $a % $n;
while ($nr != 0) {
$quot = (int) ($r / $nr);
$tmp = $nt;
$nt = $t - $quot * $nt;
$t = $tmp;
$tmp = $nr;
$nr = $r - $quot * $nr;
$r = $tmp;
}
if ($r > 1) {
return -1;
}
if ($t < 0) {
$t += $n;
}
return $t;
}
/**
* Modular implementation for negative values.
*
* @param int $a a
* @param int $b b
*
* @return int
*
* @since 1.0.0
*/
public static function mod(int $a, int $b) : int
{
if ($a < 0) {
return ($a + $b) % $b;
}
return $a % $b;
}
/**
* Modular implementation for float values
*
* @param float $a a
* @param float $b b
*
* @return float
*
* @since 1.0.0
*/
public static function modFloat(float $a, float $b) : float
{
return $a - ((int) ($a / $b)) * $b;
}
/**
* Check if value is odd.
*
* @param int $a Value to test
*
* @return bool
*
* @since 1.0.0
*/
public static function isOdd(int $a) : bool
{
return (bool) ($a & 1);
}
/**
* Check if value is even.
*
* @param int $a Value to test
*
* @return bool
*
* @since 1.0.0
*/
public static function isEven(int $a) : bool
{
return !((bool) ($a & 1));
}
/**
* Gets the relative position on a circular construct.
*
* @example The relative fiscal month (August) in a company where the fiscal year starts in July.
* @example 2 = getRelativeDegree(8, 12, 7);
*
* @param int $value Value to get degree
* @param int $length Circle size
* @param int $start Start value
*
* @return int Lowest value is 0 and highest value is length - 1
*
* @since 1.0.0
*/
public static function getRelativeDegree(int $value, int $length, int $start = 0) : int
{
return \abs(self::mod($value - $start, $length));
}
/**
* Error function coefficients for approximation
*
* @var float[]
* @since 1.0.0
*/
private const ERF_COF = [
-1.3026537197817094, 6.4196979235649026e-1,
1.9476473204185836e-2,-9.561514786808631e-3,-9.46595344482036e-4,
3.66839497852761e-4,4.2523324806907e-5,-2.0278578112534e-5,
-1.624290004647e-6,1.303655835580e-6,1.5626441722e-8,-8.5238095915e-8,
6.529054439e-9,5.059343495e-9,-9.91364156e-10,-2.27365122e-10,
9.6467911e-11, 2.394038e-12,-6.886027e-12,8.94487e-13, 3.13092e-13,
-1.12708e-13,3.81e-16,7.106e-15,-1.523e-15,-9.4e-17,1.21e-16,-2.8e-17,
];
/**
* Error function
*
* @param float $x X-Value
*
* @return float
*
* @since 1.0.0
*/
public static function getErf(float $x) : float
{
return $x > 0.0
? 1.0 - self::erfccheb($x)
: self::erfccheb(-$x) - 1.0;
}
/**
* Complementary error function
*
* @param float $x X-Value
*
* @return float
*
* @since 1.0.0
*/
public static function getErfc(float $x) : float
{
return $x > 0.0
? self::erfccheb($x)
: 2.0 - self::erfccheb(-$x);
}
/**
* Error function helper function
*
* @param float $z Z-Value
*
* @return float
*
* @throws \InvalidArgumentException
*
* @since 1.0.0
*/
private static function erfccheb(float $z) : float
{
$d = 0.;
$dd = 0.;
$ncof = \count(self::ERF_COF);
if ($z < 0.) {
throw new \InvalidArgumentException("erfccheb requires nonnegative argument");
}
$t = 2. / (2. + $z);
$ty = 4. * $t - 2.;
for ($j = $ncof - 1; $j > 0; --$j) {
$tmp = $d;
$d = $ty * $d - $dd + self::ERF_COF[$j];
$dd = $tmp;
}
return $t * \exp(-$z * $z + 0.5 * (self::ERF_COF[0] + $ty * $d) - $dd);
}
/**
* Inverse complementary error function
*
* @param float $p P-Value
*
* @return float
*
* @since 1.0.0
*/
public static function getInvErfc(float $p) : float
{
if ($p >= 2.0) {
return -100.;
} elseif ($p <= 0.0) {
return 100.;
}
$pp = ($p < 1.0) ? $p : 2. - $p;
$t = \sqrt(-2. * \log($pp / 2.));
$x = -0.70711 * ((2.30753 + $t * 0.27061) / (1. + $t * (0.99229 + $t * 0.04481)) - $t);
for ($j = 0; $j < 2; ++$j) {
$err = self::getErfc($x) - $pp;
$x += $err / (1.12837916709551257 * \exp(-($x * $x)) - $x * $err);
}
return $p < 1.0 ? $x : -$x;
}
/**
* Generalized hypergeometric function.
*
* pFq(a1, ..., ap; b1, ..., bq; z)
*
* @param array<int, float|int> $a Array of values
* @param array<int, float|int> $b Array of values
* @param float $z Z
*
* @return float
*
* @since 1.0.0
*/
public static function generalizedHypergeometricFunction(array $a, array $b, float $z) : float
{
$sum = 0.0;
$aProd = \array_fill(0, 20, []);
$bProd = \array_fill(0, 20, []);
for ($n = 0; $n < 20; ++$n) {
foreach ($a as $key => $value) {
$aProd[$n][$key] = $n === 0 ? 1 : $aProd[$n - 1][$key] * ($value + $n - 1);
}
foreach ($b as $key => $value) {
$bProd[$n][$key] = $n === 0 ? 1 : $bProd[$n - 1][$key] * ($value + $n - 1);
}
$temp = \array_product($aProd[$n]) / \array_product($bProd[$n]);
$sum += $temp * $z ** $n / self::fact($n);
}
return $sum;
}
}