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From Grant Ingersoll <gsing...@apache.org>
Subject Re: Functions, floats and doubles
Date Fri, 13 Nov 2009 18:43:10 GMT

On Nov 13, 2009, at 1:35 PM, Yonik Seeley wrote:

> On Fri, Nov 13, 2009 at 1:31 PM, Grant Ingersoll <gsingers@apache.org> wrote:
>> Yeah, in the end, Lucene Scorer returns a float...  However, if we allow for pseudo
fields and other capabilities, it would be nice to have doubles.
> 
> We have doubles already...  It's just that our general purpose
> functions (like sum) don't use them.
> geo functions could certainly use them.

Yep, I have a patch for the QueryParsing, etc. to allow me to get doubles from that.  It should
suffice for now.


> 
>>> But for something like gdist(point_a,point_b), the internal
>>> calculations can be done in double precision and if the result is cast
>>> to a float at the end, it should be good enough for most uses, right?
>> 
>> This is what I am doing for the specific case I'm working on, but I agree with Walter
here.  As Solr starts to evolve to power apps where you want to do complex functions based
on the results of queries, the loss of precision can be quite bad.
> 
> I agree with you all that eventually we want generic double precision support.
> What I don't understand is if anyone thinks it's a blocker for geo, and why.

Definitely not a blocker.  I'll put up a patch on https://issues.apache.org/jira/browse/SOLR-1302
and people can kick it around.
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