[Gambas-user] About financial program in Gambas

Thu Dec 17 04:21:08 CET 2009

Just to add my two cents worth, 

This problem has been around for eons and it does not only apply to
Gambas. When I was programming in Access and VB I had the same problem
even using the currency type.

I just use the Round function

Value = Round ( Number [ , Digits ] )

And I use this return variable in my database. 

This is the only way to make sure that rounding is done right. I found
that even with a currency data type it tended to truncate rather than
round.

By the way you should be able to insert into a stored procedure. I did
so in Access. In MySql I found that it has the TRUNCATE() command so you
can do this

SELECT Truncate( ((YourNumber * 10^dp) + 0.5) / (10^dp) , dp )  *this
will round correctly where dp is the number of dp that you need.

You will have to check the sql manual to see what command is supported
for your database.

On Wed, 2009-12-16 at 16:13 -0500, nando wrote:

> For your info only...
> I always use INT or LONG for accounting and money.
> So, (here in Canada), $42.87 is 4287
> I keep the tax (8%) as a float, therefore 8.25% is 8.25
> This is ok for tax because rounding is needed.
> For example:
> 
> 4287 * 8.25 = 35367.75 / 100 = 353.6775
> add .5 for 5/4 round up down
> = 354.1775
> Plase result into INT var which becomes 354
> 
> 4287 + 354 = 4641
> 
> Using Float for taxes allows for many decimal places.
> Using 100 for /100 process allows for any currencies where 
> you want more than 2 decimal places.
> 
> For correct printing without rounding errors, do not do 4287/100.
> but rather take the STR$(4287),
> then split the right two off, and place a decimal in that place.
> Perfect math and exact calculations every single time!!!
> 
> -Fernando
> 
> 
> ---------- Original Message -----------
> From: Ricardo Díaz Martín <oceanosoftlapalma at ...626...>
> To: mailing list for gambas users <gambas-user at lists.sourceforge.net>
> Sent: Wed, 16 Dec 2009 10:46:40 +0000
> Subject: Re: [Gambas-user] About financial program in Gambas
> 
> > Jean,
> > 
> > You can use numbers of decimal as you want. I you want 4 you only need to
> > divide by 1000. The only you need to decide on before insert data. If you
> > need to add more decimals in future you only have to modify a parameter in
> > your app from 2 to 4 (functions that show from database/write to database
> > currency values must read this values before show/write info) and update
> > your database multiplying cur fields by 100 (to add two digit more of
> > precision)
> > 
> > You never need truncate any value if you always use this especial currency
> > type. For example if you set decimals to 4, number 19.99657 is no possible.
> > 
> > If you need to get selling prices using four decimal coefficient, define
> > coefficient as a currency type and set your app to use 4 decimal for all
> > "currency" values
> > 
> > I hope this helps you
> > 
> > 2009/12/16 Jean-Yves F. Barbier <12ukwn at ...626...>
> > 
> > > Ricardo Díaz Martín a écrit :
> > > > Hi to all,
> > > >
> > > > I'm use gambas to write ERP applications. At the first, I got the same
> > > > problem but I decided to use long integer to save currency values. First
> > > > rigth two digits are always showed to users as decimal values.
> > > >
> > > > I'm rewrited all my apps from windows to gambas and they are working now
> > > > with no problems in customers servers.
> > > >
> > > > I allways use a function to show values in controls in app's forms that
> > > > convert database fields values showed in textboxes whose name started int
> > > > dbcur (p.e. dbcurVAT) to value div 100 and works with no problems. I use
> > > > allways the same function to write forms data to database and make the
> > > > reverse proccess.
> > >
> > > Hooo, thanks for the ad.
> > >
> > > > Its simple and works
> > >
> > > Sounds exactly like the commercial about women thin down cream we've
> > > got on tv for months (it works!) (sorry, I couldn't resist:)
> > >
> > > So you're truncating everything to 2 decimals, but as I said VAT (and as
> > > a matter of fact almost all french taxes) is *legally* up to 4 decimals;
> > > actually only 2 of them are used, but nothing's saying that tomorrow
> > > is won't be 3 or 4 really used (especially on those times where our
> > > gov morons (pleonasm) are desesperatly looking for money.)
> > >
> > > BTW, how do you truncate 19.99657? Down to 19.99 or up to 20.00?
> [WINDOWS-1252?]> > In my family's company a cent error is worth €100,000 fine...
> > >
> > > Other PB: most of results could be predictable (as of Nb of decimals),
> > > but some can't (ie: 92.95x1.196=111.1682 OR 145x1.196=173.42),
> > > maths says decimals should be dN1+dN2=5 but in these cases we only have
> > > 4 and 2 because of non-significant right zeroes, so you can't obviously
> > > truncate by adding the comma counting 5 from the right.
> > > One of the most used manner to get a selling price is to use a coefficient
> > > which has many decimals (usually a real), how do you determine where to
> > > put the comma in the resultant number??
> > >
> > > I see the possibilities, but AFAIK this is a full processor to write
> > > based on a complex numbers model, not to mention error possibilities
> > > have a tremendous cataclysmic potential in a matter where tax
> > > administration will be more than happy to chop your head and piss
> > > on your brain (yeah, they're like that here: when they come it is
> > > not to search, it is to find; no matter if has real justification or not.)
> > >
> > > But may be I'm totally mistaking: I always have had PBs with simple
> > > things.
> > >
> > > JY
> > > --
> > > God is real, unless declared integer.
> > >
> > >
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