commons-math-legacy/src/test/java/org/apache/commons/math4/legacy/ml/distance/EuclideanDistanceTest.java

/*
 * 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.math4.legacy.ml.distance;

import org.junit.Assert;
import org.junit.Test;
import org.apache.commons.math4.legacy.core.jdkmath.AccurateMath;

/**
 * Tests for {@link EuclideanDistance} class.
 */
public class EuclideanDistanceTest {
    private final DistanceMeasure distance = new EuclideanDistance();

    @Test
    public void testZero() {
        final double[] a = { 0, 1, -2, 3.4, 5, -6.7, 89 };
        Assert.assertEquals(0, distance.compute(a, a), 0d);
    }

    @Test
    public void test() {
        final double[] a = { 1, -2, 3, 4 };
        final double[] b = { -5, -6, 7, 8 };
        final double expected = AccurateMath.sqrt(84);
        Assert.assertEquals(expected, distance.compute(a, b), 0d);
        Assert.assertEquals(expected, distance.compute(b, a), 0d);
    }
}