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. -- View this message in context: http://postgresql.1045698.n5.nabble.com/GENARAL-round-bug-tp5800087p5800121.html Sent from the PostgreSQL - general mailing list archive at Nabble.com. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
