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de.lmu.ifi.dbs.elki.math.linearalgebra.pca.weightfunctions
Class QuadraticStddevWeight

java.lang.Object
  extended by de.lmu.ifi.dbs.elki.math.linearalgebra.pca.weightfunctions.QuadraticStddevWeight
All Implemented Interfaces:
WeightFunction

public final class QuadraticStddevWeight
extends Object
implements WeightFunction

Quadratic weight function, scaled using the standard deviation. We needed another scaling here, we chose the cutoff point to be 3*stddev. If you need another value, you have to reimplement this class. max(0.0, 1.0 - (distance/(3*stddev))^2

Author:
Erich Schubert

Field Summary
private static double scaling
          Scaling: at scaling * stddev the function will hit 0.0
 
Constructor Summary
QuadraticStddevWeight()
           
 
Method Summary
 double getWeight(double distance, double max, double stddev)
          Evaluate weight function at given parameters. max is ignored.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

scaling

private static final double scaling
Scaling: at scaling * stddev the function will hit 0.0

See Also:
Constant Field Values
Constructor Detail

QuadraticStddevWeight

public QuadraticStddevWeight()
Method Detail

getWeight

public double getWeight(double distance,
                        double max,
                        double stddev)
Evaluate weight function at given parameters. max is ignored.

Specified by:
getWeight in interface WeightFunction
Parameters:
distance - distance of the query point
max - maximum distance of all included points
stddev - standard deviation (i.e. quadratic mean / RMS) of the included points
Returns:
weight for the query point

Release 0.3 (2010-03-31_1612)