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