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Java example source code file (FastHadamardTransformerTest.java)

This example Java source code file (FastHadamardTransformerTest.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

fasthadamardtransformer, fasthadamardtransformertest, illegalargumentexception, test

The FastHadamardTransformerTest.java Java example source code

/*
 * 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.math3.transform;

import org.apache.commons.math3.util.Precision;
import org.junit.Assert;
import org.junit.Test;


/**
 * JUnit Test for HadamardTransformerTest
 * @see org.apache.commons.math3.transform.FastHadamardTransformer
 */
public final class FastHadamardTransformerTest {

    /**
     * Test of transformer for the a 8-point FHT (means n=8)
     */
    @Test
    public void test8Points() {
        checkAllTransforms(new int[] { 1, 4, -2, 3, 0, 1, 4, -1 },
                       new int[] { 10, -4, 2, -4, 2, -12, 6, 8 });
    }

    /**
     * Test of transformer for the a 4-points FHT (means n=4)
     */
    @Test
    public void test4Points() {
        checkAllTransforms(new int[] { 1, 2, 3, 4 },
                           new int[] { 10, -2, -4, 0 });
    }

    /**
     * Test the inverse transform of an integer vector is not always an integer vector
     */
    @Test
    public void testNoIntInverse() {
        FastHadamardTransformer transformer = new FastHadamardTransformer();
        double[] x = transformer.transform(new double[] { 0, 1, 0, 1}, TransformType.INVERSE);
        Assert.assertEquals( 0.5, x[0], 0);
        Assert.assertEquals(-0.5, x[1], 0);
        Assert.assertEquals( 0.0, x[2], 0);
        Assert.assertEquals( 0.0, x[3], 0);
    }

    /**
     * Test of transformer for wrong number of points
     */
    @Test
    public void test3Points() {
        try {
            new FastHadamardTransformer().transform(new double[3], TransformType.FORWARD);
            Assert.fail("an exception should have been thrown");
        } catch (IllegalArgumentException iae) {
            // expected
        }
    }

    private void checkAllTransforms(int[]x, int[] y) {
        checkDoubleTransform(x, y);
        checkInverseDoubleTransform(x, y);
        checkIntTransform(x, y);
    }

    private void checkDoubleTransform(int[]x, int[] y) {
        // Initiate the transformer
        FastHadamardTransformer transformer = new FastHadamardTransformer();

        // check double transform
        double[] dX = new double[x.length];
        for (int i = 0; i < dX.length; ++i) {
            dX[i] = x[i];
        }
        double dResult[] = transformer.transform(dX, TransformType.FORWARD);
        for (int i = 0; i < dResult.length; i++) {
            // compare computed results to precomputed results
            Assert.assertTrue(Precision.equals(y[i], dResult[i], 1));
        }
    }

    private void checkIntTransform(int[]x, int[] y) {
        // Initiate the transformer
        FastHadamardTransformer transformer = new FastHadamardTransformer();

        // check integer transform
        int iResult[] = transformer.transform(x);
        for (int i = 0; i < iResult.length; i++) {
            // compare computed results to precomputed results
            Assert.assertEquals(y[i], iResult[i]);
        }

    }

    private void checkInverseDoubleTransform(int[]x, int[] y) {
        // Initiate the transformer
        FastHadamardTransformer transformer = new FastHadamardTransformer();

        // check double transform
        double[] dY = new double[y.length];
        for (int i = 0; i < dY.length; ++i) {
            dY[i] = y[i];
        }
        double dResult[] = transformer.transform(dY, TransformType.INVERSE);
        for (int i = 0; i < dResult.length; i++) {
            // compare computed results to precomputed results
            Assert.assertTrue(Precision.equals(x[i], dResult[i], 1));
        }

    }

}

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