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/*
 * Carrot2 project.
 *
 * Copyright (C) 2002-2021, Dawid Weiss, Stanisław Osiński.
 * All rights reserved.
 *
 * Refer to the full license file "carrot2.LICENSE"
 * in the root folder of the repository checkout or at:
 * https://www.carrot2.org/carrot2.LICENSE
 */
package org.carrot2.math;

/** Some simple mathematical computation utility methods. */
public final class MathUtils {
  private MathUtils() {}

  /**
   * Returns the harmonic mean of v1 and v2, giving both arguments equal
   * weight.
   */
  public static double harmonicMean(double v1, double v2) {
    return harmonicMean(v1, v2, 1, 1);
  }

  /**
   * Returns the harmonic mean of v1 and v2, weighting them by w1
   *  and w2, respectively.
   */
  public static double harmonicMean(double v1, double v2, double w1, double w2) {
    return (w1 + w2) / (w1 / v1 + w2 / v2);
  }

  /**
   * Returns the arithmetic mean of v1 and v2, weighting them by w1
   *  and w2, respectively.
   */
  public static double arithmeticMean(double v1, double v2, double w1, double w2) {
    return (v1 * w1 + v2 * w2) / (w1 + w2);
  }
}