Re: BUG in postgres mathematic

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>
To: "Robert B. Easter" <reaster@comptechnews.com>
Cc: Max Vaschenko <max@nino.ru>, pgsql-bugs@postgresql.org
Date: 2001-01-26T03:52:30Z
Lists: pgsql-bugs
"Robert B. Easter" <reaster@comptechnews.com> writes:
> This problem is not specific to Postgres.

The fact that 5*27.81*100 != 27.81*100*5 is certainly a garden-variety
floating-point roundoff error.  However, I think Max has a fair
complaint here: it seems float-to-int8 conversion is truncating, not
rounding like the other conversions to integer do.

regression=# select 4.7::float8::int4;
 ?column?
----------
        5
(1 row)

regression=# select 4.7::float8::int8;
 ?column?
----------
        4
(1 row)

Seems to me this is a bug we should fix.

			regards, tom lane