Raymond O'Donnell wrote
> On 15/04/2014 17:20, David G Johnston wrote:
>> Willy-Bas Loos-3 wrote
>>> Hi, I ran into some strange behavior. Seems like a bug to me?
>>>
>>> wbloos=# select round(0.5::numeric), round(0.5::double precision);
>>> round | round -------+------- 1 | 0 (1 row)
>>
>> Not a bug; and likely to simple to have escaped notice this long so
>> the first reaction should be "what am I missing here?"
>>
>> [google: round .5 postgresql]
>>
>> http://grokbase.com/t/postgresql/pgsql-hackers/03ap11tckn/round-function-wrong/oldest
>>
>> Round( numeric ) - 0.5 rounds away from zero Round( float ) -
>> platform dependent, IEEE 0.5 rounds toward even
>>
>> You can argue the decision but at this point it's not likely to
>> change.
>
> Interestingly, I get different results (on both 9.1.4 and 9.3.0) on
> Windows:
>
> postgres=# select round(0.5::numeric), round(0.5::double precision);
> round | round
> -------+-------
> 1 | 1
> (1 row)
>
>
> postgres=# select version();
> version
> -------------------------------------------------------------
> PostgreSQL 9.1.4, compiled by Visual C++ build 1500, 64-bit
> (1 row)
>
>
> .... Same on 9.3.0.
I'm not particularly surprised that Windows is not being IEEE compliant, and
instead chooses the more common round-away-from-zero behavior, here though I
am unsure where the dependent implementation would end up existing.
David J.
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