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Java example source code file (UnivariateSolverUtilsTest.java)

This example Java source code file (UnivariateSolverUtilsTest.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

mathillegalargumentexception, quinticfunction, sin, test, univariatefunction, univariatesolverutilstest

The UnivariateSolverUtilsTest.java Java example source code

/*
 * 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.math3.analysis.solvers;

import org.apache.commons.math3.analysis.QuinticFunction;
import org.apache.commons.math3.analysis.UnivariateFunction;
import org.apache.commons.math3.analysis.function.Sin;
import org.apache.commons.math3.exception.MathIllegalArgumentException;
import org.apache.commons.math3.exception.NoBracketingException;
import org.apache.commons.math3.util.FastMath;
import org.junit.Assert;
import org.junit.Test;

/**
 */
public class UnivariateSolverUtilsTest {

    protected UnivariateFunction sin = new Sin();

    @Test(expected=MathIllegalArgumentException.class)
    public void testSolveNull() {
        UnivariateSolverUtils.solve(null, 0.0, 4.0);
    }

    @Test(expected=MathIllegalArgumentException.class)
    public void testSolveBadEndpoints() {
        double root = UnivariateSolverUtils.solve(sin, 4.0, -0.1, 1e-6);
        System.out.println("root=" + root);
    }

    @Test
    public void testSolveBadAccuracy() {
        try { // bad accuracy
            UnivariateSolverUtils.solve(sin, 0.0, 4.0, 0.0);
//             Assert.fail("Expecting MathIllegalArgumentException"); // TODO needs rework since convergence behaviour was changed
        } catch (MathIllegalArgumentException ex) {
            // expected
        }
    }

    @Test
    public void testSolveSin() {
        double x = UnivariateSolverUtils.solve(sin, 1.0, 4.0);
        Assert.assertEquals(FastMath.PI, x, 1.0e-4);
    }

    @Test(expected=MathIllegalArgumentException.class)
    public void testSolveAccuracyNull()  {
        double accuracy = 1.0e-6;
        UnivariateSolverUtils.solve(null, 0.0, 4.0, accuracy);
    }

    @Test
    public void testSolveAccuracySin() {
        double accuracy = 1.0e-6;
        double x = UnivariateSolverUtils.solve(sin, 1.0,
                4.0, accuracy);
        Assert.assertEquals(FastMath.PI, x, accuracy);
    }

    @Test(expected=MathIllegalArgumentException.class)
    public void testSolveNoRoot() {
        UnivariateSolverUtils.solve(sin, 1.0, 1.5);
    }

    @Test
    public void testBracketSin() {
        double[] result = UnivariateSolverUtils.bracket(sin,
                0.0, -2.0, 2.0);
        Assert.assertTrue(sin.value(result[0]) < 0);
        Assert.assertTrue(sin.value(result[1]) > 0);
    }

    @Test
    public void testBracketCentered() {
        double initial = 0.1;
        double[] result = UnivariateSolverUtils.bracket(sin, initial, -2.0, 2.0, 0.2, 1.0, 100);
        Assert.assertTrue(result[0] < initial);
        Assert.assertTrue(result[1] > initial);
        Assert.assertTrue(sin.value(result[0]) < 0);
        Assert.assertTrue(sin.value(result[1]) > 0);
    }

    @Test
    public void testBracketLow() {
        double initial = 0.5;
        double[] result = UnivariateSolverUtils.bracket(sin, initial, -2.0, 2.0, 0.2, 1.0, 100);
        Assert.assertTrue(result[0] < initial);
        Assert.assertTrue(result[1] < initial);
        Assert.assertTrue(sin.value(result[0]) < 0);
        Assert.assertTrue(sin.value(result[1]) > 0);
    }

    @Test
    public void testBracketHigh(){
        double initial = -0.5;
        double[] result = UnivariateSolverUtils.bracket(sin, initial, -2.0, 2.0, 0.2, 1.0, 100);
        Assert.assertTrue(result[0] > initial);
        Assert.assertTrue(result[1] > initial);
        Assert.assertTrue(sin.value(result[0]) < 0);
        Assert.assertTrue(sin.value(result[1]) > 0);
    }

    @Test(expected=NoBracketingException.class)
    public void testBracketLinear(){
        UnivariateSolverUtils.bracket(new UnivariateFunction() {
            public double value(double x) {
                return 1 - x;
            }
        }, 1000, Double.NEGATIVE_INFINITY, Double.POSITIVE_INFINITY, 1.0, 1.0, 100);
    }

    @Test
    public void testBracketExponential(){
        double[] result = UnivariateSolverUtils.bracket(new UnivariateFunction() {
            public double value(double x) {
                return 1 - x;
            }
        }, 1000, Double.NEGATIVE_INFINITY, Double.POSITIVE_INFINITY, 1.0, 2.0, 10);
        Assert.assertTrue(result[0] <= 1);
        Assert.assertTrue(result[1] >= 1);
    }

    @Test
    public void testBracketEndpointRoot() {
        double[] result = UnivariateSolverUtils.bracket(sin, 1.5, 0, 2.0);
        Assert.assertEquals(0.0, sin.value(result[0]), 1.0e-15);
        Assert.assertTrue(sin.value(result[1]) > 0);
    }

    @Test(expected=MathIllegalArgumentException.class)
    public void testNullFunction() {
        UnivariateSolverUtils.bracket(null, 1.5, 0, 2.0);
    }

    @Test(expected=MathIllegalArgumentException.class)
    public void testBadInitial() {
        UnivariateSolverUtils.bracket(sin, 2.5, 0, 2.0);
    }

    @Test(expected=MathIllegalArgumentException.class)
    public void testBadAdditive() {
        UnivariateSolverUtils.bracket(sin, 1.0, -2.0, 3.0, -1.0, 1.0, 100);
    }

    @Test(expected=NoBracketingException.class)
    public void testIterationExceeded() {
        UnivariateSolverUtils.bracket(sin, 1.0, -2.0, 3.0, 1.0e-5, 1.0, 100);
    }

    @Test(expected=MathIllegalArgumentException.class)
    public void testBadEndpoints() {
        // endpoints not valid
        UnivariateSolverUtils.bracket(sin, 1.5, 2.0, 1.0);
    }

    @Test(expected=MathIllegalArgumentException.class)
    public void testBadMaximumIterations() {
        // bad maximum iterations
        UnivariateSolverUtils.bracket(sin, 1.5, 0, 2.0, 0);
    }

    /** check the search continues when a = lowerBound and b < upperBound. */
    @Test
    public void testBracketLoopConditionForB() {
        double[] result = UnivariateSolverUtils.bracket(sin, -0.9, -1, 1, 0.1, 1, 100);
        Assert.assertTrue(result[0] <= 0);
        Assert.assertTrue(result[1] >= 0);
    }

    @Test
    public void testMisc() {
        UnivariateFunction f = new QuinticFunction();
        double result;
        // Static solve method
        result = UnivariateSolverUtils.solve(f, -0.2, 0.2);
        Assert.assertEquals(result, 0, 1E-8);
        result = UnivariateSolverUtils.solve(f, -0.1, 0.3);
        Assert.assertEquals(result, 0, 1E-8);
        result = UnivariateSolverUtils.solve(f, -0.3, 0.45);
        Assert.assertEquals(result, 0, 1E-6);
        result = UnivariateSolverUtils.solve(f, 0.3, 0.7);
        Assert.assertEquals(result, 0.5, 1E-6);
        result = UnivariateSolverUtils.solve(f, 0.2, 0.6);
        Assert.assertEquals(result, 0.5, 1E-6);
        result = UnivariateSolverUtils.solve(f, 0.05, 0.95);
        Assert.assertEquals(result, 0.5, 1E-6);
        result = UnivariateSolverUtils.solve(f, 0.85, 1.25);
        Assert.assertEquals(result, 1.0, 1E-6);
        result = UnivariateSolverUtils.solve(f, 0.8, 1.2);
        Assert.assertEquals(result, 1.0, 1E-6);
        result = UnivariateSolverUtils.solve(f, 0.85, 1.75);
        Assert.assertEquals(result, 1.0, 1E-6);
        result = UnivariateSolverUtils.solve(f, 0.55, 1.45);
        Assert.assertEquals(result, 1.0, 1E-6);
        result = UnivariateSolverUtils.solve(f, 0.85, 5);
        Assert.assertEquals(result, 1.0, 1E-6);
    }
}

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