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From Grant Ingersoll <gsing...@apache.org>
Subject Re: Functions, floats and doubles
Date Fri, 13 Nov 2009 18:31:43 GMT

On Nov 13, 2009, at 12:58 PM, Yonik Seeley wrote:

> On Fri, Nov 13, 2009 at 12:52 PM, Grant Ingersoll <gsingers@apache.org> wrote:
>> Implementing my first function (distance stuff) and notices that functions seem to
have a float bent to them.  Not even sure what would be involved, but there are cases for
distance that I could see wanting double precision.  Thoughts?
> 
> 
> It's an issue in general.

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.

> 
> 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.

-Grant


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