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//   http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.commons.math.optimization.fitting;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;

import java.util.Random;

import org.apache.commons.math.optimization.OptimizationException;
import org.apache.commons.math.optimization.general.LevenbergMarquardtOptimizer;
import org.apache.commons.math.util.MathUtils;
import org.junit.Test;

public class HarmonicFitterTest {

	@Test
	public void testNoError() throws OptimizationException {
		HarmonicFunction f = new HarmonicFunction(0.2, 3.4, 4.1);

		HarmonicFitter fitter = new HarmonicFitter(new LevenbergMarquardtOptimizer());
		for (double x = 0.0; x < 1.3; x += 0.01) {
			fitter.addObservedPoint(1.0, x, f.value(x));
		}

		HarmonicFunction fitted = fitter.fit();
		assertEquals(f.getAmplitude(), fitted.getAmplitude(), 1.0e-13);
		assertEquals(f.getPulsation(), fitted.getPulsation(), 1.0e-13);
		assertEquals(f.getPhase(), MathUtils.normalizeAngle(fitted.getPhase(), f.getPhase()), 1.0e-13);

		for (double x = -1.0; x < 1.0; x += 0.01) {
			assertTrue(Math.abs(f.value(x) - fitted.value(x)) < 1.0e-13);
		}

	}

	@Test
	public void test1PercentError() throws OptimizationException {
		Random randomizer = new Random(64925784252l);
		HarmonicFunction f = new HarmonicFunction(0.2, 3.4, 4.1);

		HarmonicFitter fitter = new HarmonicFitter(new LevenbergMarquardtOptimizer());
		for (double x = 0.0; x < 10.0; x += 0.1) {
			fitter.addObservedPoint(1.0, x, f.value(x) + 0.01 * randomizer.nextGaussian());
		}

		HarmonicFunction fitted = fitter.fit();
		assertEquals(f.getAmplitude(), fitted.getAmplitude(), 7.6e-4);
		assertEquals(f.getPulsation(), fitted.getPulsation(), 2.7e-3);
		assertEquals(f.getPhase(), MathUtils.normalizeAngle(fitted.getPhase(), f.getPhase()), 1.3e-2);

	}

	@Test
	public void testInitialGuess() throws OptimizationException {
		Random randomizer = new Random(45314242l);
		HarmonicFunction f = new HarmonicFunction(0.2, 3.4, 4.1);

		HarmonicFitter fitter = new HarmonicFitter(new LevenbergMarquardtOptimizer(), new double[] { 0.15, 3.6, 4.5 });
		for (double x = 0.0; x < 10.0; x += 0.1) {
			fitter.addObservedPoint(1.0, x, f.value(x) + 0.01 * randomizer.nextGaussian());
		}

		HarmonicFunction fitted = fitter.fit();
		assertEquals(f.getAmplitude(), fitted.getAmplitude(), 1.2e-3);
		assertEquals(f.getPulsation(), fitted.getPulsation(), 3.3e-3);
		assertEquals(f.getPhase(), MathUtils.normalizeAngle(fitted.getPhase(), f.getPhase()), 1.7e-2);

	}

	@Test
	public void testUnsorted() throws OptimizationException {
		Random randomizer = new Random(64925784252l);
		HarmonicFunction f = new HarmonicFunction(0.2, 3.4, 4.1);

		HarmonicFitter fitter = new HarmonicFitter(new LevenbergMarquardtOptimizer());

		// build a regularly spaced array of measurements
		int size = 100;
		double[] xTab = new double[size];
		double[] yTab = new double[size];
		for (int i = 0; i < size; ++i) {
			xTab[i] = 0.1 * i;
			yTab[i] = f.value(xTab[i]) + 0.01 * randomizer.nextGaussian();
		}

		// shake it
		for (int i = 0; i < size; ++i) {
			int i1 = randomizer.nextInt(size);
			int i2 = randomizer.nextInt(size);
			double xTmp = xTab[i1];
			double yTmp = yTab[i1];
			xTab[i1] = xTab[i2];
			yTab[i1] = yTab[i2];
			xTab[i2] = xTmp;
			yTab[i2] = yTmp;
		}

		// pass it to the fitter
		for (int i = 0; i < size; ++i) {
			fitter.addObservedPoint(1.0, xTab[i], yTab[i]);
		}

		HarmonicFunction fitted = fitter.fit();
		assertEquals(f.getAmplitude(), fitted.getAmplitude(), 7.6e-4);
		assertEquals(f.getPulsation(), fitted.getPulsation(), 3.5e-3);
		assertEquals(f.getPhase(), MathUtils.normalizeAngle(fitted.getPhase(), f.getPhase()), 1.5e-2);

	}

}
