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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 com.softsynth.math.FourierMath;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import static org.junit.jupiter.api.Assertions.assertEquals;
public class TestFFT {
private static final Logger LOGGER = LoggerFactory.getLogger(TestFFT.class);
public void checkSingleSineDouble(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);
assertEquals(0.0, magnitudes[bin-1], 0.000001, "magnitude");
assertEquals(amplitude, magnitudes[bin], 0.000001, "magnitude");
assertEquals(0.0, magnitudes[bin+1], 0.000001, "magnitude");
/*
for (int i = 0; i < magnitudes.length; i++) {
System.out.printf("%d = %9.7f\n", i, magnitudes[i]);
}
*/
}
public void checkSingleSineFloat(int size, int bin) {
float[] ar = new float[size];
float[] ai = new float[size];
float[] magnitudes = new float[size];
double amplitude = 1.0;
addSineWave(size, bin, ar, amplitude);
FourierMath.transform(1, size, ar, ai);
FourierMath.calculateMagnitudes(ar, ai, magnitudes);
assertEquals(0.0f, magnitudes[bin-1], 0.000001, "magnitude");
assertEquals(amplitude, magnitudes[bin], 0.000001, "magnitude");
assertEquals(0.0f, magnitudes[bin+1], 0.000001, "magnitude");
/*
for (int i = 0; i < magnitudes.length; i++) {
System.out.printf("%d = %9.7f\n", i, magnitudes[i]);
}
*/
}
public void checkMultipleSine(int size, int[] bins, double[] amplitudes) {
double[] ar = new double[size];
double[] ai = new double[size];
double[] magnitudes = new double[size];
for(int i = 0; i<bins.length; i++) {
addSineWave(size, bins[i], ar, amplitudes[i]);
}
FourierMath.transform(1, size, ar, ai);
FourierMath.calculateMagnitudes(ar, ai, magnitudes);
for(int bin = 0; bin<size; bin++) {
System.out.printf("%d = %9.7f\n", bin, magnitudes[bin]);
double amplitude = 0.0;
for(int i = 0; i<bins.length; i++) {
if ((bin == bins[i]) || (bin == (size - bins[i]))) {
amplitude = amplitudes[i];
break;
}
}
assertEquals(amplitude, magnitudes[bin], 0.000001, "magnitude");
}
}
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;
phase += phaseIncrement;
}
}
private void addSineWave(int size, int bin, float[] ar, double amplitude) {
double phase = 0.0;
double phaseIncrement = 2.0 * Math.PI * bin / size;
for (int i = 0; i < size; i++) {
ar[i] += (float) (Math.sin(phase) * amplitude);
phase += phaseIncrement;
}
}
public void testSinglesDouble() {
checkSingleSineDouble(32, 1);
checkSingleSineDouble(32, 4);
checkSingleSineDouble(64, 5);
checkSingleSineDouble(256, 3);
}
public void testSinglesFloat() {
checkSingleSineFloat(32, 1);
checkSingleSineFloat(32, 4);
checkSingleSineFloat(64, 5);
checkSingleSineFloat(256, 3);
}
public void testMultipleSines32() {
int[] bins = { 1, 5 };
double[] amplitudes = { 1.0, 2.0 };
checkMultipleSine(32, bins, amplitudes);
}
public void testMultipleSines64() {
int[] bins = { 2, 4, 7 };
double[] amplitudes = { 1.0, 0.3, 0.5 };
checkMultipleSine(64, bins, amplitudes);
}
public void checkInverseFftDouble(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 checkInverseFftFloat(int size, int bin) {
float[] ar1 = new float[size];
float[] ai1 = new float[size];
float[] ar2 = new float[size];
float[] ai2 = new float[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 testInverseDouble() {
checkInverseFftDouble(32, 1);
checkInverseFftDouble(32, 2);
checkInverseFftDouble(128, 17);
checkInverseFftDouble(512, 23);
}
public void testInverseFloat() {
checkInverseFftFloat(32, 1);
checkInverseFftFloat(32, 2);
checkInverseFftFloat(128, 17);
checkInverseFftFloat(512, 23);
}
}
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