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005    // to you under the Apache License, Version 2.0 (the
006    // "License"); you may not use this file except in compliance
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008    // 
009    //   http://www.apache.org/licenses/LICENSE-2.0
010    // 
011    // Unless required by applicable law or agreed to in writing,
012    // software distributed under the License is distributed on an
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014    // KIND, either express or implied.  See the License for the
015    // specific language governing permissions and limitations
016    // under the License.
017    
018    package org.apache.commons.math.optimization.fitting;
019    
020    import static org.junit.Assert.assertEquals;
021    import static org.junit.Assert.assertTrue;
022    
023    import java.util.Random;
024    
025    import org.apache.commons.math.optimization.OptimizationException;
026    import org.apache.commons.math.optimization.general.LevenbergMarquardtOptimizer;
027    import org.apache.commons.math.util.MathUtils;
028    import org.junit.Test;
029    
030    public class HarmonicFitterTest {
031    
032        @Test
033        public void testNoError() throws OptimizationException {
034            HarmonicFunction f = new HarmonicFunction(0.2, 3.4, 4.1);
035    
036            HarmonicFitter fitter =
037                new HarmonicFitter(new LevenbergMarquardtOptimizer());
038            for (double x = 0.0; x < 1.3; x += 0.01) {
039                fitter.addObservedPoint(1.0, x, f.value(x));
040            }
041    
042            HarmonicFunction fitted = fitter.fit();
043            assertEquals(f.getAmplitude(), fitted.getAmplitude(), 1.0e-13);
044            assertEquals(f.getPulsation(), fitted.getPulsation(), 1.0e-13);
045            assertEquals(f.getPhase(),     MathUtils.normalizeAngle(fitted.getPhase(), f.getPhase()), 1.0e-13);
046    
047            for (double x = -1.0; x < 1.0; x += 0.01) {
048                assertTrue(Math.abs(f.value(x) - fitted.value(x)) < 1.0e-13);
049            }
050    
051        }
052    
053        @Test
054        public void test1PercentError() throws OptimizationException {
055            Random randomizer = new Random(64925784252l);
056            HarmonicFunction f = new HarmonicFunction(0.2, 3.4, 4.1);
057    
058            HarmonicFitter fitter =
059                new HarmonicFitter(new LevenbergMarquardtOptimizer());
060            for (double x = 0.0; x < 10.0; x += 0.1) {
061                fitter.addObservedPoint(1.0, x,
062                                       f.value(x) + 0.01 * randomizer.nextGaussian());
063            }
064    
065            HarmonicFunction fitted = fitter.fit();
066            assertEquals(f.getAmplitude(), fitted.getAmplitude(), 7.6e-4);
067            assertEquals(f.getPulsation(), fitted.getPulsation(), 2.7e-3);
068            assertEquals(f.getPhase(),     MathUtils.normalizeAngle(fitted.getPhase(), f.getPhase()), 1.3e-2);
069    
070        }
071    
072        @Test
073        public void testInitialGuess() throws OptimizationException {
074            Random randomizer = new Random(45314242l);
075            HarmonicFunction f = new HarmonicFunction(0.2, 3.4, 4.1);
076    
077            HarmonicFitter fitter =
078                new HarmonicFitter(new LevenbergMarquardtOptimizer(), new double[] { 0.15, 3.6, 4.5 });
079            for (double x = 0.0; x < 10.0; x += 0.1) {
080                fitter.addObservedPoint(1.0, x,
081                                       f.value(x) + 0.01 * randomizer.nextGaussian());
082            }
083    
084            HarmonicFunction fitted = fitter.fit();
085            assertEquals(f.getAmplitude(), fitted.getAmplitude(), 1.2e-3);
086            assertEquals(f.getPulsation(), fitted.getPulsation(), 3.3e-3);
087            assertEquals(f.getPhase(),     MathUtils.normalizeAngle(fitted.getPhase(), f.getPhase()), 1.7e-2);
088    
089        }
090    
091        @Test
092        public void testUnsorted() throws OptimizationException {
093            Random randomizer = new Random(64925784252l);
094            HarmonicFunction f = new HarmonicFunction(0.2, 3.4, 4.1);
095    
096            HarmonicFitter fitter =
097                new HarmonicFitter(new LevenbergMarquardtOptimizer());
098    
099            // build a regularly spaced array of measurements
100            int size = 100;
101            double[] xTab = new double[size];
102            double[] yTab = new double[size];
103            for (int i = 0; i < size; ++i) {
104                xTab[i] = 0.1 * i;
105                yTab[i] = f.value(xTab[i]) + 0.01 * randomizer.nextGaussian();
106            }
107    
108            // shake it
109            for (int i = 0; i < size; ++i) {
110                int i1 = randomizer.nextInt(size);
111                int i2 = randomizer.nextInt(size);
112                double xTmp = xTab[i1];
113                double yTmp = yTab[i1];
114                xTab[i1] = xTab[i2];
115                yTab[i1] = yTab[i2];
116                xTab[i2] = xTmp;
117                yTab[i2] = yTmp;
118            }
119    
120            // pass it to the fitter
121            for (int i = 0; i < size; ++i) {
122                fitter.addObservedPoint(1.0, xTab[i], yTab[i]);
123            }
124    
125            HarmonicFunction fitted = fitter.fit();
126            assertEquals(f.getAmplitude(), fitted.getAmplitude(), 7.6e-4);
127            assertEquals(f.getPulsation(), fitted.getPulsation(), 3.5e-3);
128            assertEquals(f.getPhase(),     MathUtils.normalizeAngle(fitted.getPhase(), f.getPhase()), 1.5e-2);
129    
130        }
131    
132    }