Re: Rounding to even for numeric data type
От | James Cloos |
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Тема | Re: Rounding to even for numeric data type |
Дата | |
Msg-id | m3sicna8gg.fsf@carbon.jhcloos.org обсуждение исходный текст |
Ответ на | Re: Rounding to even for numeric data type (Michael Paquier <michael.paquier@gmail.com>) |
Ответы |
Re: Rounding to even for numeric data type
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Список | pgsql-hackers |
>>>>> "MP" == Michael Paquier <michael.paquier@gmail.com> writes: MP> So, attached is a patch that does 1) and 2) to make clear to the MP> user how numeric and double precision behave regarding rounding. MP> I am adding it to CF 2015-06 to keep track of it... Given that the examples show -2.5 rounds to -3, the IEEE term is roundTiesToAway, and the typical conversational english is round ties away from zero. RoundUp means mean towards +Infinity. 754 specifies that for decimal, either roundTiesToEven or roundTiesToAway are acceptable defaults, and which of the two applies is language dependent. Does ANSI SQL say anything about how numeric should round? In general, for decimals (or anything other than binary), there are twelve possible roundings: ToEven ToOdd AwayFromZero ToZero Up DownTiesToEven TiesToOdd TiesAwayFromZero TiesToZero TiesUp TiesDown (Up is the same as ceil(3), Down as floor(3).) -JimC -- James Cloos <cloos@jhcloos.com> OpenPGP: 0x997A9F17ED7DAEA6
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