/**
* Returns the dimensionless dimension.
*
* @return Dimension
*/
public static function NONE()
{
if (!is_object(self::$none)) {
self::$none = new self(SystemOfUnits::ONE());
}
return self::$none;
}
public function getBaseUnits()
{
/** @var CompoundUnit $result */
$result = SystemOfUnits::ONE();
foreach ($this->elements as $element) {
$unit = $element->unit->getBaseUnits();
$unit = $unit->pow($element->pow);
$unit = $unit->root($element->root);
$result = $result->times($unit);
}
return $result;
}
public function inverse()
{
return CompoundBuilder::getQuotientInstance(SystemOfUnits::ONE(), $this);
}
/**
* Merges the given elements.
*
* @param CompoundElement[] $leftElements
* @param CompoundElement[] $rightElements
* @param string $quantity
* @param string $symbol
*
* @return CompoundUnit
*/
private static function getInstance(array $leftElements, array $rightElements, $quantity = '', $symbol = '')
{
$result = [];
foreach ($leftElements as $leftElement) {
$pow1 = $leftElement->pow;
$root1 = $leftElement->root;
$pow2 = 0;
$root2 = 1;
foreach ($rightElements as $rightElement) {
if ($leftElement->unit->equals($rightElement->unit)) {
$pow2 = $rightElement->pow;
$root2 = $rightElement->root;
break;
}
}
$pow = $pow1 * $root2 + $pow2 * $root1;
$root = $root1 * $root2;
if ($pow != 0) {
$gcd = self::gcd(abs($pow), $root);
$result[] = new CompoundElement($leftElement->unit, $pow / $gcd, $root / $gcd);
}
}
foreach ($rightElements as $rightElement) {
$hasBeenMerged = false;
foreach ($leftElements as $leftElement) {
if ($rightElement->unit->equals($leftElement->unit)) {
$hasBeenMerged = true;
break;
}
}
if (!$hasBeenMerged) {
$result[] = $rightElement;
}
}
if (count($result) == 0) {
return SystemOfUnits::ONE();
}
if (count($result) == 1 && $result[0]->pow == $result[0]->root) {
return $result[0]->unit;
}
return new CompoundUnit($result, $quantity, $symbol);
}
