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RE: [xsl] Rounding errors in financial app transforms
Subject: RE: [xsl] Rounding errors in financial app transforms
From: "Michael Kay" <mike@xxxxxxxxxxxx>
Date: Thu, 26 Jul 2007 14:51:53 +0100
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> MulDiv, as, for example the Windows API function,
>
> "The MulDiv function multiplies two 32-bit values and then
> divides the 64-bit result by a third 32-bit value.
> The return value is rounded up or down to the nearest integer."
>
The specs do say that implementations must support 18 digits of precision
for xs:integer, so it's very likely they will use 64 bits or more. There's
no absolute rule that intermediate results of xs:integer calculations must
retain at least 64 bits, but it's a reasonable expectation. xs:decimal
leaves more scope for implementations to vary, especially with division and
in their overflow behaviour, but I think you'd be unlikely to find an
implementation that doesn't allow any two 32-bit values to be multiplied
without loss.
Michael Kay
http://www.saxonica.com/
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