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From svilen ...@svilendobrev.com>
Subject Re: Fixed precision of floating point number not respected in views
Date Wed, 20 Feb 2013 04:10:31 GMT
well then avoid floating point as representation. 
it is not keeping the input 100%, by design - no matter what language.
Either use text - "1.1" - or fake-fixed-point via integer -
e.g. "1100" for 3 digits after point. 
or both, i.e. keep the textual input separately from machine
representation. 

svil

On Wed, 20 Feb 2013 14:58:41 +1100
Luca Morandini <lmorandini@ieee.org> wrote:

> On 02/20/2013 02:01 PM, Jens Alfke wrote:
> >
> > On Feb 19, 2013, at 12:46 PM, Luca Morandini
> > <lmorandini@ieee.org> wrote:
> >
> >> Well, there it goes my academic track paper on CouchDB and
> >> GeoCouch for FOSS4G '13 :(
> >
> > Are roundoff errors on the order of one part in 2^56 really a
> > deal-breaker for your application? I mean, “17.300000000000000711”
> > does _look_ ugly compared to “17.3”, but the difference is
> > completely negligible for most purposes. Have you worked out how
> > many significant figures of accuracy you need, and are the results
> > correct to within those significant figures?
> 
> Well, it is not a matter of precision -as it may be enough for most
> purposes- but of external representation: every user would expect to
> get back the same data he had put into the database.
> 
> Another issue is the sheer size of produced JSON: we use a lot of
> geo-spatial data, and chopping off digits would be a performance boon.
> 
> Regards,
> 
> Luca Morandini
> Data Architect - AURIN project
> Department of Computing and Information Systems
> University of Melbourne
> Tel. +61 03 903 58 380
> Skype: lmorandini
> 

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