From: Tom Lane <tgl@sss.pgh.pa.us>
To: He Weiping(Laser Henry) <laser@zhengmai.com.cn>
Cc: pgsql-docs@postgresql.org
Subject: Re: some errors and/or bugs?
Date: Mon, 18 Dec 2000 20:02:49 -0500
Message-ID: <2639.977187769@sss.pgh.pa.us> (raw)
In-Reply-To: <3A3EB05E.C564D84A@zhengmai.com.cn>
References: <3A3EB05E.C564D84A@zhengmai.com.cn>
"He Weiping(Laser Henry)" <laser@zhengmai.com.cn> writes:
> laser_zh=# select round(42.5);
> round
> -------
> 42
> (1 row)
>
> is it correct? I think result should be 43.
It's correct, if the underlying float arithmetic is IEEE-compliant.
Rounding for exact half-integral values is supposed to be "round to
nearest even". So 42.5 goes to 42, but 43.5 goes to 44.
I notice our NUMERIC rounding code does not do that ... perhaps it
should.
Also, the numeric round() function is just plain broken:
regression=# select round(42.5::numeric);
ERROR: Function 'numeric_round(numeric, int4)' does not exist
Unable to identify a function that satisfies the given argument types
You may need to add explicit typecasts
regression=# select round(42.5::numeric,0);
round
-------
43
(1 row)
Looks like a silly oversight in the pg_proc entry for round(numeric).
regards, tom lane
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To: pgsql-docs@postgresql.org
Cc: tgl@sss.pgh.pa.us, laser@zhengmai.com.cn
Subject: Re: some errors and/or bugs?
In-Reply-To: <2639.977187769@sss.pgh.pa.us>
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