Subject: Re: [xsl] Rounding errors in financial app transforms From: Justin Johansson <procode@xxxxxxxxxx> Date: Fri, 27 Jul 2007 00:25:12 +0900 
David, My apologies, I should have posed the question as, "What exactly is the problem with division before I, AND OTHERS, go off thinking that all is home and hosed with xs:decimal?" noting that there are many people who read the transactions of this list without actively participating, such as people who are confused by + and  zero as demonstrated just a day or so ago. Your answer provides insight to all, and best of all, in language understood by everybody. Thanks At 03:38 PM 26/07/2007 +0100, you wrote: > >> What's exactly is the problem with division > >multiplication you can always do, so long as you have enough precision >to hold the answer. > > >Unless you are dividing by 2 you can't ever do division exactly. 1 / 10 >is 0.1 and that just can't be stored in binary arithemetic to any finite >precision. So if you need to emulate BCD arithmetic _exactly_ you need >to do arithematic using exponents being powers of 10 rather than 2, >which means that you need to encode numbers as two integers, mantisa and >(base 10) exponent. But since your financial calculation may well be >going to finally round to only a couple of sp anyway, in all practical >cases you probably get more than enough accuracy using xsd:decimal. > >David > >> (coming a company called from The Numerical Algorithms Group) ... > >Although actually before I started on this XML lark I was a pure >mathematician not a nuerical analyst. Working in finite fields is so >much easier (especially F_2 where you only have 0 and 1 to deal with:) > > >________________________________________________________________________ >The Numerical Algorithms Group Ltd is a company registered in England >and Wales with company number 1249803. The registered office is: >Wilkinson House, Jordan Hill Road, Oxford OX2 8DR, United Kingdom. > >This email has been scanned for all viruses by Star. The service is >powered by MessageLabs. >________________________________________________________________________ > > > Justin Johansson *** A horse with no name is called Lambda ***
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