| Subject | Re: [ib-support] Really strange calculating behaviour of IB |
|---|---|
| Author | Helen Borrie |
| Post date | 2002-02-13T03:02:58Z |
At 02:28 AM 14-02-02 +0100, Guido Kapperich wrote:
Read Geoff Worboys' TI on numerics, downloadable from the TechInfo page of the IB Objects web site. It probably won't solve your problem but I should help you to understand what is occurring in these calcs and to get an idea of how you need to define and constrain numeric data that is close to or beyond the bounds of you precision capabilities.
H.
All for Open and Open for All
Firebird Open SQL Database ยท http://firebirdsql.org
_______________________________________________________
>I have the following queryIB is getting it "wrong" because you give it no choice. You are "using up" 5 digits for scale, leaving 11 maximum for precision. By applying a division with a scale of 5, your result will be numeric(8,10) and so your precision is getting messed up in astronomical proportions.
>select to1valuens as DM,(to1valuens/1.95583) as EURO
>from TURNOVER_CS_MP_MONTH
>where to1csid=6 and to1paid=1 and to1mpid=2
>
>and the result
>DM EURO
>
> 149.115,080000 76.241,329768
> -77.374,130000 -1.834,082566
> 80.532,730000 41.175,731020
> 205.586,430000 105.114,672543
> 284.087,030000 145.251,391992
> 711.952,750000 364.015,660870
> 212.314,730000 108.554,797707
> 576.549,930000 294.785,298313
> 404.336,820000 206.734,133335
> 327.176,500000 167.282,688168
> 288.400,760000 147.456,967119
>-190.479,560000 -3.073,947768
>
>As you can see, in the second and last row the result is wrong.
>Now I change the query a little bit
>select to1valuens as DM,(to1valuens/1.9558) as EURO
>from TURNOVER_CS_MP_MONTH
>where to1csid=6 and to1paid=1 and to1mpid=2
>
>I changed only the dividing value from 1.95583 to 1.9558 and I get the
>result
>
>DM EURO
>
> 149.115,080000 76.242,499233
> -77.374,130000 -39.561,371306
> 80.532,730000 41.176,362614
> 205.586,430000 105.116,284896
> 284.087,030000 145.253,620002
> 711.952,750000 364.021,244504
> 212.314,730000 108.556,462829
> 576.549,930000 294.789,820022
> 404.336,820000 206.737,304428
> 327.176,500000 167.285,254116
> 288.400,760000 147.459,228960
>-190.479,560000 -97.392,146436
>
>Now IB calculates right. TO1VALUENS has the type Numeric(18,5).
>Can anybody explain this to me. It has taken me 4 hours to find out,
>that IB calculates sometimes wrong :-(
Read Geoff Worboys' TI on numerics, downloadable from the TechInfo page of the IB Objects web site. It probably won't solve your problem but I should help you to understand what is occurring in these calcs and to get an idea of how you need to define and constrain numeric data that is close to or beyond the bounds of you precision capabilities.
H.
All for Open and Open for All
Firebird Open SQL Database ยท http://firebirdsql.org
_______________________________________________________