| /* |
| * 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.optim.nonlinear.scalar.noderiv; |
| |
| import java.util.Arrays; |
| import java.util.Random; |
| import org.apache.commons.rng.UniformRandomProvider; |
| import org.apache.commons.rng.simple.RandomSource; |
| import org.apache.commons.math4.analysis.MultivariateFunction; |
| import org.apache.commons.math4.util.FastMath; |
| |
| /** |
| * Utilities for testing the optimizers. |
| */ |
| class OptimTestUtils { |
| |
| static class Sphere implements MultivariateFunction { |
| |
| @Override |
| public double value(double[] x) { |
| double f = 0; |
| for (int i = 0; i < x.length; ++i) { |
| f += x[i] * x[i]; |
| } |
| return f; |
| } |
| } |
| |
| static class Cigar implements MultivariateFunction { |
| private double factor; |
| |
| Cigar() { |
| this(1e3); |
| } |
| |
| Cigar(double axisratio) { |
| factor = axisratio * axisratio; |
| } |
| |
| @Override |
| public double value(double[] x) { |
| double f = x[0] * x[0]; |
| for (int i = 1; i < x.length; ++i) { |
| f += factor * x[i] * x[i]; |
| } |
| return f; |
| } |
| } |
| |
| static class Tablet implements MultivariateFunction { |
| private double factor; |
| |
| Tablet() { |
| this(1e3); |
| } |
| |
| Tablet(double axisratio) { |
| factor = axisratio * axisratio; |
| } |
| |
| @Override |
| public double value(double[] x) { |
| double f = factor * x[0] * x[0]; |
| for (int i = 1; i < x.length; ++i) { |
| f += x[i] * x[i]; |
| } |
| return f; |
| } |
| } |
| |
| static class CigTab implements MultivariateFunction { |
| private double factor; |
| |
| CigTab() { |
| this(1e4); |
| } |
| |
| CigTab(double axisratio) { |
| factor = axisratio; |
| } |
| |
| @Override |
| public double value(double[] x) { |
| int end = x.length - 1; |
| double f = x[0] * x[0] / factor + factor * x[end] * x[end]; |
| for (int i = 1; i < end; ++i) { |
| f += x[i] * x[i]; |
| } |
| return f; |
| } |
| } |
| |
| static class TwoAxes implements MultivariateFunction { |
| |
| private double factor; |
| |
| TwoAxes() { |
| this(1e6); |
| } |
| |
| TwoAxes(double axisratio) { |
| factor = axisratio * axisratio; |
| } |
| |
| @Override |
| public double value(double[] x) { |
| double f = 0; |
| for (int i = 0; i < x.length; ++i) { |
| f += (i < x.length / 2 ? factor : 1) * x[i] * x[i]; |
| } |
| return f; |
| } |
| } |
| |
| static class ElliRotated implements MultivariateFunction { |
| private Basis B = new Basis(); |
| private double factor; |
| |
| ElliRotated() { |
| this(1e3); |
| } |
| |
| ElliRotated(double axisratio) { |
| factor = axisratio * axisratio; |
| } |
| |
| @Override |
| public double value(double[] x) { |
| double f = 0; |
| x = B.Rotate(x); |
| for (int i = 0; i < x.length; ++i) { |
| f += FastMath.pow(factor, i / (x.length - 1.)) * x[i] * x[i]; |
| } |
| return f; |
| } |
| } |
| |
| static class Elli implements MultivariateFunction { |
| |
| private double factor; |
| |
| Elli() { |
| this(1e3); |
| } |
| |
| Elli(double axisratio) { |
| factor = axisratio * axisratio; |
| } |
| |
| @Override |
| public double value(double[] x) { |
| double f = 0; |
| for (int i = 0; i < x.length; ++i) { |
| f += FastMath.pow(factor, i / (x.length - 1.)) * x[i] * x[i]; |
| } |
| return f; |
| } |
| } |
| |
| static class MinusElli implements MultivariateFunction { |
| private final Elli elli = new Elli(); |
| @Override |
| public double value(double[] x) { |
| return 1.0 - elli.value(x); |
| } |
| } |
| |
| static class DiffPow implements MultivariateFunction { |
| @Override |
| public double value(double[] x) { |
| double f = 0; |
| for (int i = 0; i < x.length; ++i) { |
| f += FastMath.pow(FastMath.abs(x[i]), 2. + 10 * (double) i |
| / (x.length - 1.)); |
| } |
| return f; |
| } |
| } |
| |
| static class SsDiffPow implements MultivariateFunction { |
| @Override |
| public double value(double[] x) { |
| double f = FastMath.pow(new DiffPow().value(x), 0.25); |
| return f; |
| } |
| } |
| |
| static class Rosen implements MultivariateFunction { |
| @Override |
| public double value(double[] x) { |
| double f = 0; |
| for (int i = 0; i < x.length - 1; i++) { |
| final double a = x[i] * x[i] - x[i + 1]; |
| final double b = x[i] - 1; |
| f += 1e2 * a * a + b * b; |
| } |
| return f; |
| } |
| } |
| |
| static class Ackley implements MultivariateFunction { |
| private double axisratio; |
| |
| Ackley(double axra) { |
| axisratio = axra; |
| } |
| |
| public Ackley() { |
| this(1); |
| } |
| |
| @Override |
| public double value(double[] x) { |
| double f = 0; |
| double res2 = 0; |
| double fac = 0; |
| for (int i = 0; i < x.length; ++i) { |
| fac = FastMath.pow(axisratio, (i - 1.) / (x.length - 1.)); |
| f += fac * fac * x[i] * x[i]; |
| res2 += FastMath.cos(2. * FastMath.PI * fac * x[i]); |
| } |
| f = (20. - 20. * FastMath.exp(-0.2 * FastMath.sqrt(f / x.length)) |
| + FastMath.exp(1.) - FastMath.exp(res2 / x.length)); |
| return f; |
| } |
| } |
| |
| static class Rastrigin implements MultivariateFunction { |
| private double axisratio; |
| private double amplitude; |
| |
| Rastrigin() { |
| this(1, 10); |
| } |
| |
| Rastrigin(double axisratio, double amplitude) { |
| this.axisratio = axisratio; |
| this.amplitude = amplitude; |
| } |
| |
| @Override |
| public double value(double[] x) { |
| double f = 0; |
| double fac; |
| for (int i = 0; i < x.length; ++i) { |
| fac = FastMath.pow(axisratio, (i - 1.) / (x.length - 1.)); |
| if (i == 0 && x[i] < 0) { |
| fac *= 1.; |
| } |
| f += fac * fac * x[i] * x[i] + amplitude |
| * (1. - FastMath.cos(2. * FastMath.PI * fac * x[i])); |
| } |
| return f; |
| } |
| } |
| |
| static class FourExtrema implements MultivariateFunction { |
| // The following function has 4 local extrema. |
| static final double xM = -3.841947088256863675365; |
| static final double yM = -1.391745200270734924416; |
| static final double xP = 0.2286682237349059125691; |
| static final double yP = -yM; |
| static final double valueXmYm = 0.2373295333134216789769; // Local maximum. |
| static final double valueXmYp = -valueXmYm; // Local minimum. |
| static final double valueXpYm = -0.7290400707055187115322; // Global minimum. |
| static final double valueXpYp = -valueXpYm; // Global maximum. |
| |
| @Override |
| public double value(double[] variables) { |
| final double x = variables[0]; |
| final double y = variables[1]; |
| return (x == 0 || y == 0) ? 0 : |
| FastMath.atan(x) * FastMath.atan(x + 2) * FastMath.atan(y) * FastMath.atan(y) / (x * y); |
| } |
| } |
| |
| static class Rosenbrock implements MultivariateFunction { |
| @Override |
| public double value(double[] x) { |
| double a = x[1] - x[0] * x[0]; |
| double b = 1.0 - x[0]; |
| return 100 * a * a + b * b; |
| } |
| } |
| |
| static class Powell implements MultivariateFunction { |
| @Override |
| public double value(double[] x) { |
| double a = x[0] + 10 * x[1]; |
| double b = x[2] - x[3]; |
| double c = x[1] - 2 * x[2]; |
| double d = x[0] - x[3]; |
| return a * a + 5 * b * b + c * c * c * c + 10 * d * d * d * d; |
| } |
| } |
| |
| static class Gaussian2D implements MultivariateFunction { |
| private final double[] maximumPosition; |
| private final double std; |
| |
| public Gaussian2D(double xOpt, double yOpt, double std) { |
| maximumPosition = new double[] { xOpt, yOpt }; |
| this.std = std; |
| } |
| |
| public double getMaximum() { |
| return value(maximumPosition); |
| } |
| |
| public double[] getMaximumPosition() { |
| return maximumPosition.clone(); |
| } |
| |
| @Override |
| public double value(double[] point) { |
| final double x = point[0], y = point[1]; |
| final double twoS2 = 2.0 * std * std; |
| return 1.0 / (twoS2 * FastMath.PI) * FastMath.exp(-(x * x + y * y) / twoS2); |
| } |
| } |
| |
| static double[] point(int n, double value) { |
| double[] ds = new double[n]; |
| Arrays.fill(ds, value); |
| return ds; |
| } |
| |
| /** Creates a RNG instance. */ |
| static UniformRandomProvider rng() { |
| return RandomSource.create(RandomSource.MWC_256); |
| } |
| |
| private static class Basis { |
| double[][] basis; |
| final Random rand = new Random(2); // use not always the same basis |
| |
| double[] Rotate(double[] x) { |
| GenBasis(x.length); |
| double[] y = new double[x.length]; |
| for (int i = 0; i < x.length; ++i) { |
| y[i] = 0; |
| for (int j = 0; j < x.length; ++j) { |
| y[i] += basis[i][j] * x[j]; |
| } |
| } |
| return y; |
| } |
| |
| void GenBasis(int DIM) { |
| if (basis != null ? basis.length == DIM : false) { |
| return; |
| } |
| |
| double sp; |
| int i, j, k; |
| |
| /* generate orthogonal basis */ |
| basis = new double[DIM][DIM]; |
| for (i = 0; i < DIM; ++i) { |
| /* sample components gaussian */ |
| for (j = 0; j < DIM; ++j) { |
| basis[i][j] = rand.nextGaussian(); |
| } |
| /* substract projection of previous vectors */ |
| for (j = i - 1; j >= 0; --j) { |
| for (sp = 0., k = 0; k < DIM; ++k) { |
| sp += basis[i][k] * basis[j][k]; /* scalar product */ |
| } |
| for (k = 0; k < DIM; ++k) { |
| basis[i][k] -= sp * basis[j][k]; /* substract */ |
| } |
| } |
| /* normalize */ |
| for (sp = 0., k = 0; k < DIM; ++k) { |
| sp += basis[i][k] * basis[i][k]; /* squared norm */ |
| } |
| for (k = 0; k < DIM; ++k) { |
| basis[i][k] /= FastMath.sqrt(sp); |
| } |
| } |
| } |
| } |
| } |