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From Luca Morandini <lmorand...@ieee.org>
Subject Re: Fixed precision of floating point number not respected in views
Date Wed, 20 Feb 2013 03:58:41 GMT
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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