[Seaside] Money ScaledDecimal is it really *appropriate* ?

[Dmitry Dorofeev]

Hi,

Assuming I have prices with 2 digits after dot I want to calculate VAT
with 4 digits precision. VAT May be shown still rounded to 2 digits,
but some clients want to see even 4 digits after dot !!! With high
turn over made from small sells it is some real money due to rounding errors :-)

I made some tests and found a funny example:

a := ScaledDecimal newFromNumber: 6.18 scale: 4.
b :=  ScaledDecimal newFromNumber: 5 scale: 4.
a / b   1.2359s4
a / b printShowingDecimalPlaces: 4 '1.2360'
6.18 / 5.0  1.236

why a / b shows 2.2359s4 ?
but (a / b printShowingDecimalPlaces: 4) shows correct answer
It makes me nervious....

Thanks.

David T. Lewis wrote:
> in Wed, Feb 01, 2006 at 02:51:42PM +0300, Dmitry Dorofeev wrote:
> 
>>Thanks,
>>
>>this one looks practical.
>>I am sad there is no Money in Squeak though...
> 
> 
> Don't be sad, there is ScaledDecimal in Squeak :)
> 
> Float is *not* appropriate for financial calculations, but
> ScaledDecimal should be OK. And #printShowingDecimalPlaces: will
> work with ScaledDecimal also:
> 
> 123.3453 asScaledDecimal printShowingDecimalPlaces: 2. ==> '123.35'
> 
> Dave
> 
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