[AccessD] Strange results with simple calculation on a form

Gustav,

thanks for your answer. I keep forgetting textboxes only contain text... i
think i will forget it this time again... ;-)
The maximum is 2 decimals so that is no problem. But since the differences
was at the 15th decimal (although i only tested this 1 time...) I decide to
add round([calculation];2) in the total field. I think this is ok because i
know only numers with 2 decimals are entered....

Bert-Jan

----- Original Message ----- 
From: "Gustav Brock" <gustav at cactus.dk>
To: "Access Developers discussion and problem solving"
<accessd at databaseadvisors.com>
Sent: Thursday, March 18, 2004 11:18 AM
Subject: Re: [AccessD] Strange results with simple calculation on a form


> Hi Bert-Jan
>
> Welcome back.
>
> Unbound textboxes contain text no matter how you format them.
> And decimals may not be exact Doubles and indeed not Singles.
>
> If you can accept a maximum of four decimals, use CCur(txtYourTextbox)
> to convert to Currency before doing any calculation or comparison.
> Else use CDbl() and compare to a max. tolerance of your choice:
>
>   If Abs(dblTotal - dblAmount) < 1E-7 Then
>     ' Values are equal.
>   End If
>
> /gustav
>
>
> > Hi all,
>
> > i was forced to unsubscribe a while ago because i couldn't keep up with
you
> > and all the messages... ;-)
>
> > But today a strange thing happened i had to ask you all about. I didn't
do a
> > big search on the internet, but searched the accessd archives and didn't
> > find it. It maybe is a well known problem, but here it goes.....
>
> > I have an unbound form where users will type amounts. All the txtboxes'
> > format are set to "standard" and the decimal places is set to 2. And i
check
> > on the before_update event of these txtboxes if there are more then 2
> > decimals, if so, cancel = true. There is an calculated total control
> > (txtTotal) wich has a controlsource like =[txtbox1]+[txtbox2] and so on
(in
> > total 12 txtboxes)
> > These txtboxes are used to 'split up' the amount in another txtbox.
> > (txtAmount)
>
> > Before saving i check if txtAmount = txtTotal. When no decimals are used
> > there is no problem, if there are only used decimals in 1 txtbox there
is no
> > problem. But if there are used decimals in more txtboxes access will
tell me
> > the values are not the same..... although the same values are shown...
it
> > turns out there is a difference of: 0.00000000000000710542735!!!!!!
> > (debug.print told me this!)
>
> > When i use the same 'function' in VBA it works fine with the same
> > values....????
>
> > So it is not a real problem, but it IS something strange... wel to me it
> > is....
>
> > Thanks in advance.
>
> > Hope to keep up with you this time... ;-)
>
> > Bert-Jan
>
> -- 
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