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From "Zhao, Xin" <xzh...@jhmi.edu>
Subject scoring formula
Date Wed, 02 Aug 2006 18:32:31 GMT
Hi,
I noticed the scoring formula in the errata of book "Lucene in Action" is a little different
from the one in Javadoc. I enclosed the one in Javadoc at the end of email. getBoost(t in
q) is in Javadoc's formula (which I assume is the correct one), but not in "lucene in action".
Any idea? We need to re-implement the scoring in our application. What I understand is for
each term in query, we should multiply the indexing boost( the boost manfully added while
indexing) with the query boost, and with term frequency, lengthnorm, idf. So the formula in
Javadoc makes more sense to me. Please correct me if I am wrong. Totally new to Lucene.
Appreciate your help,

Xin

*************************************************************

      score(q,d) =
     Σ ( tf(t in d) * idf(t)^2 * getBoost(t in q) * getBoost(t.field in d) * lengthNorm(t.field
in d) )   * coord(q,d) * queryNorm(sumOfSqaredWeights)  
      t in q  

************************************************************

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