/* Copyright 2009-2015 David Hadka
*
* This file is part of the MOEA Framework.
*
* The MOEA Framework is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or (at your
* option) any later version.
*
* The MOEA Framework 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 Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with the MOEA Framework. If not, see <http://www.gnu.org/licenses/>.
*/
package org.moeaframework;
import org.junit.Assert;
import org.moeaframework.core.Settings;
/**
* Compares floating-point numbers allowing a small relative error when
* determining equality. Using a relative error allows better scaling across
* floating-point values of varying magnitudes.
*/
public class RelativeError implements FloatingPointError {
/**
* The maximum relative error permitted when considering if two floating-
* point numbers are equal.
*/
private final double relativeError;
/**
* Creates a comparator of floating-point values allowing a small relative
* error when determining equality.
*
* @param epsilon the maximum relative error permitted when considering if
* two floating-point numbers are equal
*/
public RelativeError(double relativeError) {
super();
this.relativeError = relativeError;
}
@Override
public void assertEquals(final double d1, final double d2) {
if (Math.abs(d1 - d2) > Settings.EPS) {
double error = 0.0;
if (Math.abs(d1) > Math.abs(d2)) {
error = Math.abs((d1 - d2) / d1);
} else {
error = Math.abs((d1 - d2) / d2);
}
if (error > relativeError) {
Assert.fail("values " + d1 + " " + d2 + " differ by more than "
+ (relativeError*100.0) + "% error");
}
}
}
}