/*
* 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.math.transform;
import junit.framework.TestCase;
/**
* JUnit Test for HadamardTransformerTest
* @see org.apache.commons.math.transform.FastHadamardTransformer
*/
public final class FastHadamardTransformerTest extends TestCase {
/**
* Test of transformer for the a 8-point FHT (means n=8)
*/
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)
*/
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
*/
public void testNoIntInverse() {
FastHadamardTransformer transformer = new FastHadamardTransformer();
double[] x = transformer.inversetransform(new double[] { 0, 1, 0, 1});
assertEquals( 0.5, x[0], 0);
assertEquals(-0.5, x[1], 0);
assertEquals( 0.0, x[2], 0);
assertEquals( 0.0, x[3], 0);
}
/**
* Test of transformer for wrong number of points
*/
public void test3Points() {
try {
new FastHadamardTransformer().transform(new double[3]);
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);
for (int i = 0; i < dResult.length; i++) {
// compare computed results to precomputed results
assertEquals((double) y[i], dResult[i]);
}
}
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
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.inversetransform(dY);
for (int i = 0; i < dResult.length; i++) {
// compare computed results to precomputed results
assertEquals((double) x[i], dResult[i]);
}
}
}
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