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diff --git a/src/de/lmu/ifi/dbs/elki/math/statistics/distribution/LogLogisticDistribution.java b/src/de/lmu/ifi/dbs/elki/math/statistics/distribution/LogLogisticDistribution.java
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+package de.lmu.ifi.dbs.elki.math.statistics.distribution;
+
+/*
+ This file is part of ELKI:
+ Environment for Developing KDD-Applications Supported by Index-Structures
+
+ Copyright (C) 2013
+ 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 java.util.Random;
+
+/**
+ * Log-Logistic distribution also known as Fisk distribution.
+ * 
+ * @author Erich Schubert
+ */
+public class LogLogisticDistribution implements Distribution {
+  /**
+   * Parameters: scale and shape
+   */
+  double scale, shape;
+
+  /**
+   * Random number generator
+   */
+  Random random;
+
+  /**
+   * Constructor.
+   * 
+   * @param scale Scale
+   * @param shape Shape
+   */
+  public LogLogisticDistribution(double scale, double shape) {
+    this(scale, shape, null);
+  }
+
+  /**
+   * Constructor.
+   * 
+   * @param scale Scale
+   * @param shape Shape
+   * @param random Random number generator
+   */
+  public LogLogisticDistribution(double scale, double shape, Random random) {
+    super();
+    this.scale = scale;
+    this.shape = shape;
+    this.random = random;
+  }
+
+  /**
+   * Probability density function.
+   * 
+   * @param val Value
+   * @param scale Scale
+   * @param shape Shape
+   * @return PDF
+   */
+  public static double pdf(double val, double scale, double shape) {
+    if(val < 0) {
+      return 0;
+    }
+    val = Math.abs(val / scale);
+    double f = shape / scale * Math.pow(val, shape - 1.);
+    double d = 1. + Math.pow(val, shape);
+    return f / (d * d);
+  }
+
+  @Override
+  public double pdf(double val) {
+    return pdf(val, scale, shape);
+  }
+
+  /**
+   * Cumulative density function.
+   * 
+   * @param val Value
+   * @param scale Scale
+   * @param shape Shape
+   * @return CDF
+   */
+  public static double cdf(double val, double scale, double shape) {
+    if(val < 0) {
+      return 0;
+    }
+    return 1. / (1. + Math.pow(val / scale, -shape));
+  }
+
+  @Override
+  public double cdf(double val) {
+    return cdf(val, scale, shape);
+  }
+
+  /**
+   * Quantile function.
+   * 
+   * @param val Value
+   * @param scale Scale
+   * @param shape Shape
+   * @return Quantile
+   */
+  public static double quantile(double val, double scale, double shape) {
+    return scale * Math.pow(val / (1. - val), 1. / shape);
+  }
+
+  @Override
+  public double quantile(double val) {
+    return quantile(val, scale, shape);
+  }
+
+  @Override
+  public double nextRandom() {
+    double u = random.nextDouble();
+    return scale * Math.pow(u / (1. - u), 1. / shape);
+  }
+
+  @Override
+  public String toString() {
+    return "LogLogisticDistribution(scale=" + scale + ", shape=" + shape + ")";
+  }
+}