RoundingMode.php
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<?php
declare(strict_types=1);
namespace Brick\Math;
/**
* Specifies a rounding behavior for numerical operations capable of discarding precision.
*
* Each rounding mode indicates how the least significant returned digit of a rounded result
* is to be calculated. If fewer digits are returned than the digits needed to represent the
* exact numerical result, the discarded digits will be referred to as the discarded fraction
* regardless the digits' contribution to the value of the number. In other words, considered
* as a numerical value, the discarded fraction could have an absolute value greater than one.
*/
final class RoundingMode
{
/**
* Private constructor. This class is not instantiable.
*
* @codeCoverageIgnore
*/
private function __construct()
{
}
/**
* Asserts that the requested operation has an exact result, hence no rounding is necessary.
*
* If this rounding mode is specified on an operation that yields a result that
* cannot be represented at the requested scale, a RoundingNecessaryException is thrown.
*/
public const UNNECESSARY = 0;
/**
* Rounds away from zero.
*
* Always increments the digit prior to a nonzero discarded fraction.
* Note that this rounding mode never decreases the magnitude of the calculated value.
*/
public const UP = 1;
/**
* Rounds towards zero.
*
* Never increments the digit prior to a discarded fraction (i.e., truncates).
* Note that this rounding mode never increases the magnitude of the calculated value.
*/
public const DOWN = 2;
/**
* Rounds towards positive infinity.
*
* If the result is positive, behaves as for UP; if negative, behaves as for DOWN.
* Note that this rounding mode never decreases the calculated value.
*/
public const CEILING = 3;
/**
* Rounds towards negative infinity.
*
* If the result is positive, behave as for DOWN; if negative, behave as for UP.
* Note that this rounding mode never increases the calculated value.
*/
public const FLOOR = 4;
/**
* Rounds towards "nearest neighbor" unless both neighbors are equidistant, in which case round up.
*
* Behaves as for UP if the discarded fraction is >= 0.5; otherwise, behaves as for DOWN.
* Note that this is the rounding mode commonly taught at school.
*/
public const HALF_UP = 5;
/**
* Rounds towards "nearest neighbor" unless both neighbors are equidistant, in which case round down.
*
* Behaves as for UP if the discarded fraction is > 0.5; otherwise, behaves as for DOWN.
*/
public const HALF_DOWN = 6;
/**
* Rounds towards "nearest neighbor" unless both neighbors are equidistant, in which case round towards positive infinity.
*
* If the result is positive, behaves as for HALF_UP; if negative, behaves as for HALF_DOWN.
*/
public const HALF_CEILING = 7;
/**
* Rounds towards "nearest neighbor" unless both neighbors are equidistant, in which case round towards negative infinity.
*
* If the result is positive, behaves as for HALF_DOWN; if negative, behaves as for HALF_UP.
*/
public const HALF_FLOOR = 8;
/**
* Rounds towards the "nearest neighbor" unless both neighbors are equidistant, in which case rounds towards the even neighbor.
*
* Behaves as for HALF_UP if the digit to the left of the discarded fraction is odd;
* behaves as for HALF_DOWN if it's even.
*
* Note that this is the rounding mode that statistically minimizes
* cumulative error when applied repeatedly over a sequence of calculations.
* It is sometimes known as "Banker's rounding", and is chiefly used in the USA.
*/
public const HALF_EVEN = 9;
}