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Posted to dev@lucene.apache.org by "Mark Miller (JIRA)" <ji...@apache.org> on 2009/02/02 18:33:59 UTC

[jira] Commented: (LUCENE-1534) idf(t) is not actually squared during scoring?

    [ https://issues.apache.org/jira/browse/LUCENE-1534?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12669663#action_12669663 ] 

Mark Miller commented on LUCENE-1534:
-------------------------------------

hmmm...we do multiply it in twice, but a bit happens in between - we multiply by idf(t) in sumOfSquaredWeights()  and then again in normalize(float queryNorm).

Technically that is boost * idf(t) * norm * idf(t), right? For idf(t)^2 * boost * norm? And then that times tf in the scorer... 

> idf(t) is not actually squared during scoring?
> ----------------------------------------------
>
>                 Key: LUCENE-1534
>                 URL: https://issues.apache.org/jira/browse/LUCENE-1534
>             Project: Lucene - Java
>          Issue Type: Bug
>          Components: Query/Scoring
>    Affects Versions: 2.1, 2.2, 2.3, 2.3.1, 2.3.2, 2.4
>            Reporter: Michael McCandless
>            Assignee: Michael McCandless
>            Priority: Minor
>             Fix For: 2.9
>
>
> The javadocs for Similarity:
>   http://lucene.apache.org/java/2_4_0/api/org/apache/lucene/search/Similarity.html
> show idf(t) as being squared when computing net query score.  But I
> don't think it is actually squared, in looking at the sources?  Maybe
> it used to be, eg this interesting discussion:
>   http://markmail.org/message/k5pl7scmiac5wosb
> Or am I missing something?  We just need to fix the javadocs to take
> away the "squared"...

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