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/*
* Copyright 2009 Phil Burk, Mobileer Inc
*
* Licensed 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 com.jsyn.util;
import junit.framework.TestCase;
import com.softsynth.math.FourierMath;
public class TestFFT extends TestCase {
@Override
protected void setUp() throws Exception {
super.setUp();
}
@Override
protected void tearDown() throws Exception {
super.tearDown();
}
public void checkSingleSine(int size, int bin) {
double[] ar = new double[size];
double[] ai = new double[size];
double[] magnitudes = new double[size];
double amplitude = 1.0;
addSineWave(size, bin, ar, amplitude);
FourierMath.transform(1, size, ar, ai);
FourierMath.calculateMagnitudes(ar, ai, magnitudes);
assertTrue(magnitudes[bin - 1] < 0.001);
assertTrue(magnitudes[bin] > 0.5);
assertTrue(magnitudes[bin + 1] < 0.001);
}
private void addSineWave(int size, int bin, double[] ar, double amplitude) {
double phase = 0.0;
double phaseIncrement = 2.0 * Math.PI * bin / size;
for (int i = 0; i < size; i++) {
ar[i] += Math.sin(phase) * amplitude;
// System.out.println( i + " = " + ar[i] );
phase += phaseIncrement;
}
}
public void testSingles() {
checkSingleSine(32, 1);
checkSingleSine(32, 2);
checkSingleSine(64, 5);
checkSingleSine(256, 3);
}
public void checkInverseFFT(int size, int bin) {
double[] ar1 = new double[size];
double[] ai1 = new double[size];
double[] ar2 = new double[size];
double[] ai2 = new double[size];
double amplitude = 1.0;
addSineWave(size, bin, ar1, amplitude);
// Save a copy of the source.
System.arraycopy(ar1, 0, ar2, 0, size);
System.arraycopy(ai1, 0, ai2, 0, size);
FourierMath.transform(1, size, ar1, ai1); // FFT
FourierMath.transform(-1, size, ar1, ai1); // IFFT
for (int i = 0; i < size; i++) {
assertEquals(ar2[i], ar1[i], 0.00001);
assertEquals(ai2[i], ai1[i], 0.00001);
}
}
public void testInverse() {
checkInverseFFT(32, 1);
checkInverseFFT(32, 2);
checkInverseFFT(128, 17);
checkInverseFFT(512, 23);
}
}
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