Re: strange sum behaviour

["Andrew Baerg" <andrew.baerg@xxxxxxxxx>]

Thanks for so many prompt responses. I have researched the differences
between floating point and arbitrary precision numbers in the pgsql
docs and understand now what is happening.

Thanks again to the many great members of the pgsql community.

Andrew

On 8/29/06, Andrew Baerg <andrew.baerg@xxxxxxxxx> wrote:
> Hi,
>
> I am getting strange results from the sum function as follows:
>
> corp=# select amount from acc_trans where trans_id=19721 and chart_id=10019;
>  amount
> ---------
>     4.88
>    117.1
>  -121.98
> (3 rows)
>
> corp=# select sum(amount) from acc_trans where trans_id=19721 and
> chart_id=10019;
>          sum
> ----------------------
>  -1.4210854715202e-14
> (1 row)
>
>
> amount is defined as double precision. I noticed that if I cast amount
> as numeric, the sum comes out 0 as expected.
>
> I am using postgresql 8.0.1
>
> Thanks in advance for any help or suggestions.
>
> Andrew Baerg