diff --git a/src/java/org/apache/solr/search/function/ReciprocalFloatFunction.java b/src/java/org/apache/solr/search/function/ReciprocalFloatFunction.java index b33850f53b2..a72dcf21af4 100644 --- a/src/java/org/apache/solr/search/function/ReciprocalFloatFunction.java +++ b/src/java/org/apache/solr/search/function/ReciprocalFloatFunction.java @@ -25,17 +25,20 @@ import java.util.Map; /** * ReciprocalFloatFunction 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}. *
* * 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. - *
These properties make this an idea function for boosting more recent documents. - *
Example:ReciprocalFloatFunction(new ReverseOrdFieldSource("my_date"),1,1000,1000) + *

These properties make this an idea function for boosting more recent documents. + *

Example: recip(ms(NOW,mydatefield),3.16e-11,1,1) + *

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 {