Dear Ken,
reply goes to the list if you don't mind :)
----- Original Message -----
From: "Kenneth Marshall" <ktm@it.is.rice.edu>
To: "SZŰCS Gábor" <surrano@mailbox.hu>
Sent: Tuesday, October 28, 2003 4:45 PM
> Postgres is using the standard definition of rounding. What you
The "standard" definition I know states that 0.5 should round *up*, not
*away from zero*. i.e. 3.5 rounds (up) to 4, and -3.5 rounds (up) to -3. I
was just wondering if there is an explicit/official claim that Postgres does
round away from zero.
> cannot see is that the float values are not actually exactly 0.5
Yes I could guess that (floating point vs fixed), but is this a coincidence
that both '0.5'::float and '-0.5'::float are closer to 0, whereas they could
be closer to +/-1, as well as both closer to the lower or upper bound.
This is why I asked if it's intentional/guaranteed, or undefined -- say, a
future change in glibc may cause this to change.
> I cannot imagine that the behavior would ever change.
If you can tell the developers' opinion for sure, that's enough for me :)
G.
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