/*
* This file is part of Caliph & Emir.
*
* Caliph & Emir is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* Caliph & Emir is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Caliph & Emir; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Copyright statement:
* --------------------
* (c) 2002-2005 by Mathias Lux (mathias@juggle.at)
* http://www.juggle.at, http://caliph-emir.sourceforge.net
*/
package at.lux.retrieval.fastmap;
import at.lux.retrieval.calculations.DistanceMatrix;
/**
* Date: 07.02.2005
* Time: 22:06:25
*
* @author Mathias Lux, mathias@juggle.at
*/
public interface FastmapDistanceMatrix extends DistanceMatrix {
/**
* Calculates and returns the distance between two objects. Please note that the
* distance function has to be symmetric and must obey the triangle inequality.
* distance in k is: d[k+1](o1,o2)^2 = d[k](o1,o2)^2 - (x1[k]-x2[k])^2 .
*
* @param index1 index of first object to compute
* @param index2 index of second object to compute
* @param k defines the dimension of current fastmap operation
* @param x1 is needed when k > 0 (see documentation above), all x1[l] with l < k have to be present.
* @param x2 is needed when k > 0 (see documentation above), all x2[l] with l < k have to be present.
* @return the distance as float from [0, infinite)
*/
float getDistance(int index1, int index2, int k, float[] x1, float[] x2);
/**
* Used for the heuristic for getting the pivots as described in the paper.
*
* @param row defines the row where we want to find the maximum
* @param k defines the dimension of current fastmap operation
* @param points is needed when k > 0 (see documentation above), all x1[l] with l < k have to be present.
* @return the index of the object with maximum distance to the row object.
*/
int getMaximumDistance(int row, int k, float[][] points);
/**
* Normalizes the matrix for all values to [0,1]
*/
public void normalize();
}