Hi,

> Ok. Take the following query:
>
> select txamount from laytransactions where layid = 5
>
> The result is:
>
> -7.34
> 7.34
> -29.36
> -8.09
> 37.49
> -0.04
>
> Now, I run the following query:
>
> select sum(txamount) from laytransactions where layid = 5
>
> The result is:
>
> -8.53483950180589E-16
>
> What the heck? Why isn't it zero???
>
> I am using FB 1.0. The txamount column is a double precision. But,
> shouldn't summing a bunch of numbers with exactly 2 decimal places yield a
> result with two digits, and not some random very small number???

Have you ever read some documentation on FLOATs (as a double prec. is a
floating point value) and computers? If not, use Google and read some.

Floats are aproximate values - anything can happen with them. Heck, if I
do: myfloatvar := 1.23 --> it can store anything _close_ to 1.23 ...

If you want precise math, use integers or other fixed point stuff, like
NUMERIC(10, 2) or something (dialect 3 dbs).


With regards,

Martijn Tonies
InterBase Workbench - the developer tool for InterBase & Firebird
Firebird Workbench - the developer tool for Firebird
Upscene Productions
http://www.upscene.com

"This is an object-oriented system.
If we change anything, the users object."