Re: (Bug) Numeric fault calculation - Mailing list pgadmin-support

From Alexander Yerenkow
Subject Re: (Bug) Numeric fault calculation
Date
Msg-id CAPJF9w=_XekyYy5R8MUhOKdxdA9RbCTHkU_723Y-Cc35GDTrUA@mail.gmail.com
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In response to (Bug) Numeric fault calculation  ("Kanitchet Vaiassava" <kanichet@hotmail.com>)
List pgadmin-support
Try

select (260739.94::double precision * (1.00::double precision / 365.00::double precision) )

default precision in postgres is pretty lossy, use double precision whenever you need max precision.




2013/4/23 Kanitchet Vaiassava <kanichet@hotmail.com>
(Bug) Numeric fault calculation
 
My company has using postgresql as database for ERP application which in-house developed.
For store financial and accounting data, we chose "numeric" type for accurate calculation (and with recommend by postgres's documentation) and we faced the problem by using "double precision" before.
 
However, we found that by using numeric had the problem too.
In our formula for calculate interest for customer's overdue payment that using numeric,
we found that it had fault calculate. So, it effected our interest amount.
 
In the attached file you can see that the result from postgresql and by using long division method is difference.
 
postgresql : 714.35599999999xxxx
long division method: 714.356
 
and if we multiply this result with interest rate and others factor and round up later. the amount is miscalculate.
 
Thank you and sorry for bad english gramma.
 
 
Best Regards,
Kanitchet Vaiassava
ThaiAce Group
555 Nawamin Rd., Klongkum, Buengkum, Bangkok 10230, Thailand
Mobile +66 89 515 9955; Office +66 2 744 2288; Fax +66 2 379 1166
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Regards,
Alexander Yerenkow

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