| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You 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 org.apache.commons.math4.legacy.optim.nonlinear.scalar; |
| |
| import java.util.function.Supplier; |
| import org.apache.commons.geometry.euclidean.twod.Vector2D; |
| import org.apache.commons.math4.legacy.analysis.MultivariateFunction; |
| import org.apache.commons.math4.legacy.optim.InitialGuess; |
| import org.apache.commons.math4.legacy.optim.MaxEval; |
| import org.apache.commons.math4.legacy.optim.PointValuePair; |
| import org.apache.commons.math4.legacy.optim.SimpleValueChecker; |
| import org.apache.commons.math4.legacy.optim.nonlinear.scalar.gradient.CircleScalar; |
| import org.apache.commons.math4.legacy.optim.nonlinear.scalar.gradient.NonLinearConjugateGradientOptimizer; |
| import org.apache.commons.math4.legacy.optim.nonlinear.scalar.noderiv.NelderMeadTransform; |
| import org.apache.commons.math4.legacy.optim.nonlinear.scalar.noderiv.SimplexOptimizer; |
| import org.apache.commons.math4.legacy.optim.nonlinear.scalar.noderiv.Simplex; |
| import org.apache.commons.rng.UniformRandomProvider; |
| import org.apache.commons.rng.simple.RandomSource; |
| import org.apache.commons.rng.sampling.distribution.GaussianSampler; |
| import org.apache.commons.rng.sampling.distribution.ZigguratNormalizedGaussianSampler; |
| import org.junit.Assert; |
| import org.junit.Test; |
| |
| public class MultiStartMultivariateOptimizerTest { |
| @Test |
| public void testCircleFitting() { |
| CircleScalar circle = new CircleScalar(); |
| circle.addPoint( 30.0, 68.0); |
| circle.addPoint( 50.0, -6.0); |
| circle.addPoint(110.0, -20.0); |
| circle.addPoint( 35.0, 15.0); |
| circle.addPoint( 45.0, 97.0); |
| // TODO: the wrapper around NonLinearConjugateGradientOptimizer is a temporary hack for |
| // version 3.1 of the library. It should be removed when NonLinearConjugateGradientOptimizer |
| // will officially be declared as implementing MultivariateDifferentiableOptimizer |
| GradientMultivariateOptimizer underlying |
| = new NonLinearConjugateGradientOptimizer(NonLinearConjugateGradientOptimizer.Formula.POLAK_RIBIERE, |
| new SimpleValueChecker(1e-10, 1e-10)); |
| final Supplier<double[]> generator = gaussianRandom(new double[] { 50, 50 }, |
| new double[] { 10, 10 }, |
| RandomSource.MT_64.create()); |
| int nbStarts = 10; |
| MultiStartMultivariateOptimizer optimizer |
| = new MultiStartMultivariateOptimizer(underlying, nbStarts, generator); |
| PointValuePair optimum |
| = optimizer.optimize(new MaxEval(1000), |
| circle.getObjectiveFunction(), |
| circle.getObjectiveFunctionGradient(), |
| new NelderMeadTransform(), |
| GoalType.MINIMIZE, |
| new InitialGuess(new double[] { 98.680, 47.345 })); |
| Assert.assertEquals(1000, optimizer.getMaxEvaluations()); |
| PointValuePair[] optima = optimizer.getOptima(); |
| Assert.assertEquals(nbStarts, optima.length); |
| for (PointValuePair o : optima) { |
| // we check the results of all intermediate restarts here (there are 10 such results) |
| Vector2D center = Vector2D.of(o.getPointRef()[0], o.getPointRef()[1]); |
| Assert.assertEquals(69.9597, circle.getRadius(center), 1e-3); |
| Assert.assertEquals(96.07535, center.getX(), 1.4e-3); |
| Assert.assertEquals(48.1349, center.getY(), 5e-3); |
| } |
| |
| final int numEval = optimizer.getEvaluations(); |
| Assert.assertTrue("n=" + numEval, numEval > 750); |
| Assert.assertTrue("n=" + numEval, numEval < 950); |
| |
| Assert.assertEquals(3.1267527, optimum.getValue(), 1e-8); |
| } |
| |
| @Test |
| public void testRosenbrock() { |
| Rosenbrock rosenbrock = new Rosenbrock(); |
| SimplexOptimizer underlying |
| = new SimplexOptimizer(new SimpleValueChecker(-1, 1e-3)); |
| final Simplex simplex = Simplex.of(new double[][] { |
| { -1.2, 1.0 }, |
| { 0.9, 1.2 } , |
| { 3.5, -2.3 } |
| }); |
| final Supplier<double[]> generator = gaussianRandom(new double[] { 0, 0 }, |
| new double[] { 1, 1 }, |
| RandomSource.MT_64.create()); |
| int nbStarts = 10; |
| MultiStartMultivariateOptimizer optimizer |
| = new MultiStartMultivariateOptimizer(underlying, nbStarts, generator); |
| PointValuePair optimum |
| = optimizer.optimize(new MaxEval(1100), |
| new ObjectiveFunction(rosenbrock), |
| GoalType.MINIMIZE, |
| simplex, |
| new NelderMeadTransform(), |
| new InitialGuess(new double[] { -1.2, 1.0 })); |
| Assert.assertEquals(nbStarts, optimizer.getOptima().length); |
| |
| final int numEval = optimizer.getEvaluations(); |
| Assert.assertEquals(rosenbrock.getCount(), numEval); |
| Assert.assertTrue("numEval=" + numEval, numEval > 700); |
| Assert.assertTrue("numEval=" + numEval, numEval < 1200); |
| Assert.assertTrue("optimum=" + optimum.getValue(), optimum.getValue() < 5e-5); |
| } |
| |
| private static class Rosenbrock implements MultivariateFunction { |
| private int count; |
| |
| Rosenbrock() { |
| count = 0; |
| } |
| |
| @Override |
| public double value(double[] x) { |
| ++count; |
| double a = x[1] - x[0] * x[0]; |
| double b = 1 - x[0]; |
| return 100 * a * a + b * b; |
| } |
| |
| public int getCount() { |
| return count; |
| } |
| } |
| |
| /** |
| * @param mean Means. |
| * @param stdev Standard deviations. |
| * @param rng Underlying RNG. |
| * @return a random array generator where each element is a Gaussian |
| * sampling with the given mean and standard deviation. |
| */ |
| private Supplier<double[]> gaussianRandom(final double[] mean, |
| final double[] stdev, |
| final UniformRandomProvider rng) { |
| final ZigguratNormalizedGaussianSampler normalized = new ZigguratNormalizedGaussianSampler(rng); |
| final GaussianSampler[] samplers = new GaussianSampler[mean.length]; |
| for (int i = 0; i < mean.length; i++) { |
| samplers[i] = new GaussianSampler(normalized, mean[i], stdev[i]); |
| } |
| |
| return new Supplier<double[]>() { |
| @Override |
| public double[] get() { |
| final double[] s = new double[mean.length]; |
| for (int i = 0; i < mean.length; i++) { |
| s[i] = samplers[i].sample(); |
| } |
| return s; |
| } |
| }; |
| } |
| } |