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From: cram on 13 May 2010 13:09
work with Xp and Access2003
I want to do following
In an Input form I want to check if some data aore correct. based on
invoices I introduce the BasicAmount, the txes and the total of the invoice
i.e. the sum of Basic + Taxes say i.e. 100 + 21 = 121
I intorduce the 100, the 21 and the 121. As matter of contol I compare the
calculated sum of 100+21 and compare with the inputed 121. If there is a
difference I show an error message.
My problem is now that for SOME records the message appears although the 3
inputs are correct.
As futher detail, all nummers are "single".
I'm afraid that in calculating "the sum" there must be some "distorsion"
somewhere in the decimal-figures.
Any one any idea?
--
cram
From: KARL DEWEY on 13 May 2010 16:48
You need to show us what your formulas look like.

Also post examples of the 'distortion' you are getting, input and output
numbers.

--
Build a little, test a little.


"cram" wrote:

> work with Xp and Access2003
> I want to do following
> In an Input form I want to check if some data aore correct. based on
> invoices I introduce the BasicAmount, the txes and the total of the invoice
> i.e. the sum of Basic + Taxes say i.e. 100 + 21 = 121
> I intorduce the 100, the 21 and the 121. As matter of contol I compare the
> calculated sum of 100+21 and compare with the inputed 121. If there is a
> difference I show an error message.
> My problem is now that for SOME records the message appears although the 3
> inputs are correct.
> As futher detail, all nummers are "single".
> I'm afraid that in calculating "the sum" there must be some "distorsion"
> somewhere in the decimal-figures.
> Any one any idea?
> --
> cram
From: John W. Vinson on 13 May 2010 18:46
On Thu, 13 May 2010 10:09:01 -0700, cram <cram(a)discussions.microsoft.com>
wrote:

>work with Xp and Access2003
>I want to do following
>In an Input form I want to check if some data aore correct. based on
>invoices I introduce the BasicAmount, the txes and the total of the invoice
>i.e. the sum of Basic + Taxes say i.e. 100 + 21 = 121
>I intorduce the 100, the 21 and the 121. As matter of contol I compare the
>calculated sum of 100+21 and compare with the inputed 121. If there is a
>difference I show an error message.
>My problem is now that for SOME records the message appears although the 3
>inputs are correct.
>As futher detail, all nummers are "single".
>I'm afraid that in calculating "the sum" there must be some "distorsion"
>somewhere in the decimal-figures.
>Any one any idea?

Since these values refer to money, I'd strongly suggest using the Currency
datatype rather than Number... Single. Single numbers are floating point
values; as such, some values cannot be represented accurately. 100 and 21
should work, but (for instance)

?csng(3.1) + csng(5.3) - 8.4
9.53674312853536E-08

Single *IS AN APPROXIMATION*, accurate to about 7 decimal places, and as you
see, not always exact!

Using Currency datatype avoids this issue:

?ccur(3.1) + ccur(5.3) - 8.4
0

--

John W. Vinson [MVP]
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