Author: yonik
Date: Sun Oct 18 21:35:35 2009
New Revision: 826529
URL: http://svn.apache.org/viewvc?rev=826529&view=rev
Log:
javadoc - new ms() based example for date boosting
Modified:
lucene/solr/trunk/src/java/org/apache/solr/search/function/ReciprocalFloatFunction.java
Modified:
lucene/solr/trunk/src/java/org/apache/solr/search/function/ReciprocalFloatFunction.java
URL:
http://svn.apache.org/viewvc/lucene/solr/trunk/src/java/org/apache/solr/search/function/ReciprocalFloatFunction.java?rev=826529&r1=826528&r2=826529&view=diff
==============================================================================
---
lucene/solr/trunk/src/java/org/apache/solr/search/function/ReciprocalFloatFunction.java
(original)
+++
lucene/solr/trunk/src/java/org/apache/solr/search/function/ReciprocalFloatFunction.java
Sun Oct 18 21:35:35 2009
@@ -25,17 +25,20 @@
/**
* <code>ReciprocalFloatFunction</code> implements a reciprocal function f(x)
= a/(mx+b), based on
- * the float value of a field as exported by {...@link
org.apache.solr.search.function.ValueSource}.
+ * the float value of a field or function as exported by {...@link
org.apache.solr.search.function.ValueSource}.
* <br>
*
* When a and b are equal, and x>=0, this function has a maximum value of 1
that drops as x increases.
* Increasing the value of a and b together results in a movement of the
entire function to a flatter part of the curve.
- * <br>These properties make this an idea function for boosting more recent
documents.
- * <br>Example:<code>ReciprocalFloatFunction(new
ReverseOrdFieldSource("my_date"),1,1000,1000)</code>
+ * <p>These properties make this an idea function for boosting more recent
documents.
+ * <p>Example:<code> recip(ms(NOW,mydatefield),3.16e-11,1,1)</code>
+ * <p>A multiplier of 3.16e-11 changes the units from milliseconds to years
(since there are about 3.16e10 milliseconds
+ * per year). Thus, a very recent date will yield a value close to 1/(0+1) or
1,
+ * a date a year in the past will get a multiplier of about 1/(1+1) or 1/2,
+ * and date two years old will yield 1/(2+1) or 1/3.
*
* @see FunctionQuery
*
- *
* @version $Id$
*/
public class ReciprocalFloatFunction extends ValueSource {
