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From Yonik Seeley <yo...@lucidimagination.com>
Subject Re: Rounding errors in solr
Date Fri, 22 Jul 2011 20:27:50 GMT
On Fri, Jul 22, 2011 at 4:11 PM, Brian Lamb
<brian.lamb@journalexperts.com> wrote:
> I've noticed some peculiar scoring issues going on in my application. For
> example, I have a field that is multivalued and has several records that
> have the same value. For example,
>
> <arr name="references">
>  <str>National Society of Animal Lovers</str>
>  <str>Nat. Soc. of Ani. Lov.</str>
> </arr>
>
> I have about 300 records with that exact value.
>
> Now, when I do a search for references:(national society animal lovers), I
> get the following results:
>
> <id>252</id>
> <id>159</id>
> <id>82</id>
> <id>452</id>
> <id>105</id>
>
> When I do a search for references:(nat soc ani lov), I get the results
> ordered differently:
>
> <id>510</id>
> <id>122</id>
> <id>501</id>
> <id>82</id>
> <id>252</id>
>
> When I load all the records that match, I notice that at some point, the
> scores aren't the same but differ by only a little:
>
> 1.471928 in one and the one before it was 1.471929

32 bit floats only have 7 decimal digits of precision, and in floating
point land (a+b+c) can be slightly different than (c+b+a)

-Yonik
http://www.lucidimagination.com

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