The following bug has been logged online:

Bug reference: 2211
Logged by: Tiago D. J.
Email address: tiago (AT) mdtestudio (DOT) com.br
PostgreSQL version: 8.1
Operating system: Slackware 10.2
Description: select (1::float-1::float)*(-1) = -0 ??
Details:

Hi people,
I think that anything * 0, or 0*anything should be zero.
But run this query :
select (1::float-1::float)*(-1)

it returns -0

Sorry, my english is so poor,
I hope that i'm helping you with this information.

Tiago

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On 1/25/06, Tiago D. J. <tiago (AT) mdtestudio (DOT) com.br> wrote:
pruebas=3D# select version();
version

---------------------------------------------------------------------------=
---------------
PostgreSQL 8.1.1 on i686-pc-mingw32, compiled by GCC gcc.exe (GCC)
3.4.2 (mingw-special)
(1 fila)


pruebas=3D# select (1::float-1::float)*(-1);
?column?
----------
0
(1 fila)


This is good for me... maybe a bug already fixed?

--
regards,
Jaime Casanova
(DBA: DataBase Aniquilator

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"Tiago D. J." <tiago (AT) mdtestudio (DOT) com.br> writes:
AFAIK this is correct behavior per the IEEE floating-point-math spec.

regards, tom lane

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