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Core interfaces and classes for Apache Commons Geometry.
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.geometry.core.precision;
import java.io.Serializable;
import org.apache.commons.numbers.core.Precision;
/** Simple {@link DoublePrecisionContext} subclass that uses an absolute epsilon value to
* determine equality between doubles.
*
* This class uses the {@link Precision#compareTo(double, double, double)} method to compare
* numbers. Two values are considered equal if there is no floating point
* value strictly between them or if their numerical difference is less than or equal
* to the configured epsilon value.
*
* @see Precision#compareTo(double, double, double)
*/
public class EpsilonDoublePrecisionContext extends DoublePrecisionContext implements Serializable {
private static final long serialVersionUID = 1L;
/** Epsilon value. */
private final double epsilon;
/** Simple constructor.
* @param eps Epsilon value. Numbers are considered equal if there is no
* floating point value strictly between them or if their difference is less
* than or equal to this value.
* @throws IllegalArgumentException if the given epsilon value is infinite, NaN, or negative
*/
public EpsilonDoublePrecisionContext(final double eps) {
if (!Double.isFinite(eps) || eps < 0.0) {
throw new IllegalArgumentException("Invalid epsilon value: " + eps);
}
this.epsilon = eps;
}
/** Get the epsilon value for the instance. Numbers are considered equal if there
* is no floating point value strictly between them or if their difference is less
* than or equal to this value.
* @return the epsilon value for the instance
*/
public double getEpsilon() {
return epsilon;
}
/** {@inheritDoc}
* This value is equal to the epsilon value for the instance.
* @see #getEpsilon()
*/
@Override
public double getMaxZero() {
return getEpsilon();
}
/** {@inheritDoc} **/
@Override
public int compare(final double a, final double b) {
return Precision.compareTo(a, b, epsilon);
}
/** {@inheritDoc} **/
@Override
public int hashCode() {
int result = 31;
result += 17 * Double.hashCode(epsilon);
return result;
}
/** {@inheritDoc} **/
@Override
public boolean equals(final Object obj) {
if (this == obj) {
return true;
}
if (!(obj instanceof EpsilonDoublePrecisionContext)) {
return false;
}
final EpsilonDoublePrecisionContext other = (EpsilonDoublePrecisionContext) obj;
return Double.compare(this.epsilon, other.epsilon) == 0;
}
/** {@inheritDoc} **/
@Override
public String toString() {
final StringBuilder sb = new StringBuilder();
sb.append(this.getClass().getSimpleName())
.append("[")
.append("epsilon= ")
.append(epsilon)
.append("]");
return sb.toString();
}
}