001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.math.transform;
018
019 import org.apache.commons.math.analysis.*;
020 import org.apache.commons.math.MathException;
021 import junit.framework.TestCase;
022
023 /**
024 * Testcase for fast sine transformer.
025 * <p>
026 * FST algorithm is exact, the small tolerance number is used only
027 * to account for round-off errors.
028 *
029 * @version $Revision: 764769 $ $Date: 2009-04-14 09:13:54 -0400 (Tue, 14 Apr 2009) $
030 */
031 public final class FastSineTransformerTest extends TestCase {
032
033 /**
034 * Test of transformer for the ad hoc data.
035 */
036 public void testAdHocData() {
037 FastSineTransformer transformer = new FastSineTransformer();
038 double result[], tolerance = 1E-12;
039
040 double x[] = { 0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0 };
041 double y[] = { 0.0, 20.1093579685034, -9.65685424949238,
042 5.98642305066196, -4.0, 2.67271455167720,
043 -1.65685424949238, 0.795649469518633 };
044
045 result = transformer.transform(x);
046 for (int i = 0; i < result.length; i++) {
047 assertEquals(y[i], result[i], tolerance);
048 }
049
050 result = transformer.inversetransform(y);
051 for (int i = 0; i < result.length; i++) {
052 assertEquals(x[i], result[i], tolerance);
053 }
054
055 FastFourierTransformer.scaleArray(x, Math.sqrt(x.length / 2.0));
056
057 result = transformer.transform2(y);
058 for (int i = 0; i < result.length; i++) {
059 assertEquals(x[i], result[i], tolerance);
060 }
061
062 result = transformer.inversetransform2(x);
063 for (int i = 0; i < result.length; i++) {
064 assertEquals(y[i], result[i], tolerance);
065 }
066 }
067
068 /**
069 * Test of transformer for the sine function.
070 */
071 public void testSinFunction() throws MathException {
072 UnivariateRealFunction f = new SinFunction();
073 FastSineTransformer transformer = new FastSineTransformer();
074 double min, max, result[], tolerance = 1E-12; int N = 1 << 8;
075
076 min = 0.0; max = 2.0 * Math.PI;
077 result = transformer.transform(f, min, max, N);
078 assertEquals(N >> 1, result[2], tolerance);
079 for (int i = 0; i < N; i += (i == 1 ? 2 : 1)) {
080 assertEquals(0.0, result[i], tolerance);
081 }
082
083 min = -Math.PI; max = Math.PI;
084 result = transformer.transform(f, min, max, N);
085 assertEquals(-(N >> 1), result[2], tolerance);
086 for (int i = 0; i < N; i += (i == 1 ? 2 : 1)) {
087 assertEquals(0.0, result[i], tolerance);
088 }
089 }
090
091 /**
092 * Test of parameters for the transformer.
093 */
094 public void testParameters() throws Exception {
095 UnivariateRealFunction f = new SinFunction();
096 FastSineTransformer transformer = new FastSineTransformer();
097
098 try {
099 // bad interval
100 transformer.transform(f, 1, -1, 64);
101 fail("Expecting IllegalArgumentException - bad interval");
102 } catch (IllegalArgumentException ex) {
103 // expected
104 }
105 try {
106 // bad samples number
107 transformer.transform(f, -1, 1, 0);
108 fail("Expecting IllegalArgumentException - bad samples number");
109 } catch (IllegalArgumentException ex) {
110 // expected
111 }
112 try {
113 // bad samples number
114 transformer.transform(f, -1, 1, 100);
115 fail("Expecting IllegalArgumentException - bad samples number");
116 } catch (IllegalArgumentException ex) {
117 // expected
118 }
119 }
120 }