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<?php
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namespace Samsara\Fermat\Provider\Distribution;
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use RandomLib\Factory;
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use Samsara\Exceptions\UsageError\IntegrityConstraint;
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use Samsara\Exceptions\UsageError\OptionalExit;
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use Samsara\Fermat\Numbers;
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use Samsara\Fermat\Provider\Distribution\Base\Distribution;
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use Samsara\Fermat\Provider\StatsProvider;
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use Samsara\Fermat\Types\Base\DecimalInterface;
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use Samsara\Fermat\Types\Base\NumberCollectionInterface;
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use Samsara\Fermat\Types\Base\NumberInterface;
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use Samsara\Fermat\Types\NumberCollection;
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use Samsara\Fermat\Values\ImmutableNumber;
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class Normal extends Distribution
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{
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/**
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* @var ImmutableNumber
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*/
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private $mean;
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/**
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* @var ImmutableNumber
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*/
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private $sd;
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/**
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* Normal constructor.
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*
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* @param int|float|DecimalInterface $mean
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* @param int|float|DecimalInterface $sd
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* @throws IntegrityConstraint
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*/
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public function __construct($mean, $sd)
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{
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$mean = Numbers::makeOrDont(Numbers::IMMUTABLE, $mean);
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$sd = Numbers::makeOrDont(Numbers::IMMUTABLE, $sd);
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$this->mean = $mean;
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$this->sd = $sd;
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}
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public function getSD()
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{
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return $this->sd;
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}
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public function getMean()
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{
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return $this->mean;
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}
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/**
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* @param int|float|DecimalInterface $p
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* @param int|float|DecimalInterface $x
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* @param int|float|DecimalInterface $mean
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*
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* @return Normal
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* @throws IntegrityConstraint
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*/
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public static function makeFromMean($p, $x, $mean): Normal
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{
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$one = Numbers::makeOne();
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$p = Numbers::makeOrDont(Numbers::IMMUTABLE, $p);
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$x = Numbers::makeOrDont(Numbers::IMMUTABLE, $x);
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$mean = Numbers::makeOrDont(Numbers::IMMUTABLE, $mean);
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$z = StatsProvider::inverseNormalCDF($one->subtract($p));
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$sd = $x->subtract($mean)->divide($z);
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return new Normal($mean, $sd);
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}
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/**
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* @param int|float|DecimalInterface $p
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* @param int|float|DecimalInterface $x
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* @param int|float|DecimalInterface $sd
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*
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* @return Normal
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* @throws IntegrityConstraint
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*/
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public static function makeFromSd($p, $x, $sd): Normal
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{
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$one = Numbers::makeOne();
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$p = Numbers::makeOrDont(Numbers::IMMUTABLE, $p);
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$x = Numbers::makeOrDont(Numbers::IMMUTABLE, $x);
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$sd = Numbers::makeOrDont(Numbers::IMMUTABLE, $sd);
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$z = StatsProvider::inverseNormalCDF($one->subtract($p));
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$mean = $x->subtract($z->multiply($sd));
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return new Normal($mean, $sd);
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}
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/**
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* @param int|float|DecimalInterface $x
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*
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* @return ImmutableNumber
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* @throws IntegrityConstraint
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*/
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public function cdf($x): ImmutableNumber
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{
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$x = Numbers::makeOrDont(Numbers::IMMUTABLE, $x);
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3 |
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$oneHalf = Numbers::make(Numbers::IMMUTABLE, '0.5');
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$one = Numbers::makeOne();
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$sqrtTwo = Numbers::make(Numbers::IMMUTABLE, 2)->sqrt();
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/** @var ImmutableNumber $cdf */
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$cdf = $oneHalf->multiply($one->add(StatsProvider::gaussErrorFunction(
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$x->subtract($this->mean)->divide($this->sd->multiply($sqrtTwo))
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)));
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return $cdf;
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}
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/**
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* @param int|float|DecimalInterface $x1
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* @param null|int|float|DecimalInterface $x2
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*
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* @return ImmutableNumber
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* @throws IntegrityConstraint
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*/
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public function pdf($x1, $x2 = null): ImmutableNumber
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{
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$x1 = Numbers::makeOrDont(Numbers::IMMUTABLE, $x1);
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if (is_null($x2)) {
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$separation = $x1->subtract($this->mean)->multiply(2)->abs();
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if ($this->mean->isLessThan($x1)) {
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$x2 = $x1->subtract($separation);
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} else {
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$x2 = $x1->add($separation);
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}
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}
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/** @var ImmutableNumber $pdf */
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$pdf = $this->cdf($x1)->subtract($this->cdf($x2))->abs();
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return $pdf;
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}
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/**
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* @param int|float|DecimalInterface $x
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*
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* @return ImmutableNumber
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* @throws IntegrityConstraint
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*/
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public function percentBelowX($x): ImmutableNumber
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{
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return $this->cdf($x);
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}
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/**
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* @param int|float|DecimalInterface $x
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*
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* @return ImmutableNumber
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* @throws IntegrityConstraint
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*/
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public function percentAboveX($x): ImmutableNumber
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{
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$one = Numbers::makeOne();
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return $one->subtract($this->cdf($x));
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}
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/**
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* @param int|float|DecimalInterface $x
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*
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* @return ImmutableNumber
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* @throws IntegrityConstraint
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*/
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public function zScoreOfX($x): ImmutableNumber
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{
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/** @var ImmutableNumber $x */
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$x = Numbers::makeOrDont(Numbers::IMMUTABLE, $x);
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/** @var ImmutableNumber $z */
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$z = $x->subtract($this->mean)->divide($this->sd);
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return $z;
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}
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/**
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* @param int|float|DecimalInterface $z
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*
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* @return ImmutableNumber
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* @throws IntegrityConstraint
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*/
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public function xFromZScore($z): ImmutableNumber
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{
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$z = Numbers::makeOrDont(Numbers::IMMUTABLE, $z);
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/** @var ImmutableNumber $x */
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$x = $z->multiply($this->sd)->add($this->mean);
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return $x;
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}
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/**
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* @return ImmutableNumber
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* @throws IntegrityConstraint
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*/
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public function random(): ImmutableNumber
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{
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$randFactory = new Factory();
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$generator = $randFactory->getMediumStrengthGenerator();
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$rand1 = Numbers::make(Numbers::IMMUTABLE, $generator->generateInt(), 20);
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$rand1 = $rand1->divide(PHP_INT_MAX);
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$rand2 = Numbers::make(Numbers::IMMUTABLE, $generator->generateInt(), 20);
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$rand2 = $rand2->divide(PHP_INT_MAX);
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$randomNumber = $rand1->ln()->multiply(-2)->sqrt()->multiply($rand2->multiply(Numbers::TAU)->cos(1, false));
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/** @var ImmutableNumber $randomNumber */
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$randomNumber = $randomNumber->multiply($this->sd)->add($this->mean);
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return $randomNumber;
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}
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/**
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* @param int|float|NumberInterface $min
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* @param int|float|NumberInterface $max
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* @param int $maxIterations
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*
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* @return ImmutableNumber
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* @throws OptionalExit
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* @throws IntegrityConstraint
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*/
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public function rangeRandom($min = 0, $max = PHP_INT_MAX, int $maxIterations = 20): ImmutableNumber
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{
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$i = 0;
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do {
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$randomNumber = $this->random();
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$i++;
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} while (($randomNumber->isGreaterThan($max) || $randomNumber->isLessThan($min)) && $i < $maxIterations);
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if ($randomNumber->isGreaterThan($max) || $randomNumber->isLessThan($min)) {
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throw new OptionalExit(
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'All random numbers generated were outside of the requested range',
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'A suitable random number, restricted by the $max ('.$max.') and $min ('.$min.'), could not be found within '.$maxIterations.' iterations'
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);
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}
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return $randomNumber;
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}
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} |
Our type inference engine has found a suspicous assignment of a value to a property. This check raises an issue when a value that can be of a mixed type is assigned to a property that is type hinted more strictly.
For example, imagine you have a variable
$accountId
that can either hold an Id object or false (if there is no account id yet). Your code now assigns that value to theid
property of an instance of theAccount
class. This class holds a proper account, so the id value must no longer be false.Either this assignment is in error or a type check should be added for that assignment.