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/*
* (C) Copyright 2016-2023, by Dimitrios Michail and Contributors.
*
* JGraphT : a free Java graph-theory library
*
* See the CONTRIBUTORS.md file distributed with this work for additional
* information regarding copyright ownership.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License 2.0 which is available at
* http://www.eclipse.org/legal/epl-2.0, or the
* GNU Lesser General Public License v2.1 or later
* which is available at
* http://www.gnu.org/licenses/old-licenses/lgpl-2.1-standalone.html.
*
* SPDX-License-Identifier: EPL-2.0 OR LGPL-2.1-or-later
*/
package org.jgrapht.alg.util;
import java.io.*;
import java.util.*;
/**
* A double comparator with adjustable tolerance.
*
* @author Dimitrios Michail
*/
public class ToleranceDoubleComparator
implements Comparator, Serializable
{
private static final long serialVersionUID = -3819451375975842372L;
/**
* Default tolerance used by the comparator.
*/
public static final double DEFAULT_EPSILON = 1e-9;
private final double epsilon;
/**
* Construct a new comparator with a {@link #DEFAULT_EPSILON} tolerance.
*/
public ToleranceDoubleComparator()
{
this(DEFAULT_EPSILON);
}
/**
* Construct a new comparator with a specified tolerance.
*
* @param epsilon the tolerance
*/
public ToleranceDoubleComparator(double epsilon)
{
if (epsilon <= 0.0) {
throw new IllegalArgumentException("Tolerance must be positive");
}
this.epsilon = epsilon;
}
/**
* Compares two floating point values. Returns 0 if they are equal, -1 if {@literal o1 < o2}, 1
* otherwise
*
* @param o1 the first value
* @param o2 the second value
* @return 0 if they are equal, -1 if {@literal o1 < o2}, 1 otherwise
*/
@Override
public int compare(Double o1, Double o2)
{
if (Math.abs(o1 - o2) < epsilon) {
return 0;
} else {
return Double.compare(o1, o2);
}
}
}