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1   package org.djutils.means;
2   
3   /**
4    * Compute the harmonic (weighted) mean of a set of values.
5    * <p>
6    * Copyright (c) 2013-2024 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
7    * BSD-style license. See <a href="https://djutils.org/docs/current/djutils/licenses.html">DJUTILS License</a>.
8    * </p>
9    * @author <a href="https://www.tudelft.nl/averbraeck">Alexander Verbraeck</a>
10   * @author <a href="https://www.tudelft.nl/staff/p.knoppers/">Peter Knoppers</a>
11   * @param <V> value type
12   * @param <W> weight type
13   */
14  public class HarmonicMean<V extends Number, W extends Number> extends AbstractMean<HarmonicMean<V, W>, V, W>
15  {
16  
17      @Override
18      public final double getMean()
19      {
20          return getSumOfWeights() / getSum();
21      }
22  
23      @Override
24      public final HarmonicMean<V, W> addImpl(final V value, final Number weight)
25      {
26          increment(weight.doubleValue() / value.doubleValue(), weight.doubleValue());
27          return this;
28      }
29  
30      @Override
31      public final String toString()
32      {
33          return "HarmonicMean [current sum of reciprocal values=" + getSum() + ", current sum of weights=" + getSumOfWeights()
34                  + ", current harmonic mean=" + getMean() + "]";
35      }
36  
37  }