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diff --git a/src/de/lmu/ifi/dbs/elki/distance/similarityfunction/InvertedDistanceSimilarityFunction.java b/src/de/lmu/ifi/dbs/elki/distance/similarityfunction/InvertedDistanceSimilarityFunction.java
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+package de.lmu.ifi.dbs.elki.distance.similarityfunction;
+
+/*
+ This file is part of ELKI:
+ Environment for Developing KDD-Applications Supported by Index-Structures
+
+ Copyright (C) 2012
+ Ludwig-Maximilians-Universität München
+ Lehr- und Forschungseinheit für Datenbanksysteme
+ ELKI Development Team
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU Affero General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program 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 Affero General Public License for more details.
+
+ You should have received a copy of the GNU Affero General Public License
+ along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+import de.lmu.ifi.dbs.elki.data.type.SimpleTypeInformation;
+import de.lmu.ifi.dbs.elki.distance.distancefunction.PrimitiveDistanceFunction;
+import de.lmu.ifi.dbs.elki.distance.distancevalue.DoubleDistance;
+import de.lmu.ifi.dbs.elki.distance.distancevalue.NumberDistance;
+import de.lmu.ifi.dbs.elki.utilities.optionhandling.OptionID;
+
+/**
+ * Adapter to use a primitive number-distance as similarity measure, by computing
+ * 1/distance.
+ * 
+ * @author Erich Schubert
+ * 
+ * @param <O> Object type
+ */
+public class InvertedDistanceSimilarityFunction<O> extends AbstractPrimitiveSimilarityFunction<O, DoubleDistance> {
+  /**
+   * Parameter to specify the similarity function to derive the distance between
+   * database objects from. Must extend
+   * {@link de.lmu.ifi.dbs.elki.distance.distancefunction.DistanceFunction} .
+   * <p>
+   * Key: {@code -adapter.distancefunction}
+   * </p>
+   * <p>
+   * Default value:
+   * {@link de.lmu.ifi.dbs.elki.distance.distancefunction.EuclideanDistanceFunction}
+   * </p>
+   */
+  public static final OptionID DISTANCE_FUNCTION_ID = OptionID.getOrCreateOptionID("adapter.distancefunction", "Distance function to derive the similarity between database objects from.");
+
+  /**
+   * Holds the similarity function.
+   */
+  protected PrimitiveDistanceFunction<? super O, ? extends NumberDistance<?, ?>> distanceFunction;
+
+  @Override
+  public DoubleDistance getDistanceFactory() {
+    return DoubleDistance.FACTORY;
+  }
+
+  @Override
+  public SimpleTypeInformation<? super O> getInputTypeRestriction() {
+    return distanceFunction.getInputTypeRestriction();
+  }
+
+  @Override
+  public DoubleDistance similarity(O o1, O o2) {
+    double dist = distanceFunction.distance(o1, o2).doubleValue();
+    return new DoubleDistance(1. / dist);
+  }
+}
+\ No newline at end of file