Commons Math example source code file (LaguerreSolverTest.java)

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

Java - Commons Math tags/keywords

exception, expecting, illegalargumentexception, illegalargumentexception, laguerresolver, laguerresolver, laguerresolvertest, mathexception, mathexception, polynomialfunction, polynomialfunction, sinfunction, testcase, univariaterealsolver

The Commons Math LaguerreSolverTest.java 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.math.analysis.solvers;

import org.apache.commons.math.MathException;
import org.apache.commons.math.TestUtils;
import org.apache.commons.math.analysis.SinFunction;
import org.apache.commons.math.analysis.polynomials.PolynomialFunction;
import org.apache.commons.math.complex.Complex;
import junit.framework.TestCase;

/**
 * Testcase for Laguerre solver.
 * <p>
 * Laguerre's method is very efficient in solving polynomials. Test runs
 * show that for a default absolute accuracy of 1E-6, it generally takes
 * less than 5 iterations to find one root, provided solveAll() is not
 * invoked, and 15 to 20 iterations to find all roots for quintic function.
 *
 * @version $Revision: 811685 $ $Date: 2009-09-05 13:36:48 -0400 (Sat, 05 Sep 2009) $
 */
public final class LaguerreSolverTest extends TestCase {

    /**
     * Test deprecated APIs.
     */
    @Deprecated
    public void testDeprecated() throws MathException {
        double min, max, expected, result, tolerance;

        // p(x) = 4x - 1
        double coefficients[] = { -1.0, 4.0 };
        PolynomialFunction f = new PolynomialFunction(coefficients);
        UnivariateRealSolver solver = new LaguerreSolver(f);

        min = 0.0; max = 1.0; expected = 0.25;
        tolerance = Math.max(solver.getAbsoluteAccuracy(),
                    Math.abs(expected * solver.getRelativeAccuracy()));
        result = solver.solve(min, max);
        assertEquals(expected, result, tolerance);
    }

    /**
     * Test of solver for the linear function.
     */
    public void testLinearFunction() throws MathException {
        double min, max, expected, result, tolerance;

        // p(x) = 4x - 1
        double coefficients[] = { -1.0, 4.0 };
        PolynomialFunction f = new PolynomialFunction(coefficients);
        UnivariateRealSolver solver = new LaguerreSolver();

        min = 0.0; max = 1.0; expected = 0.25;
        tolerance = Math.max(solver.getAbsoluteAccuracy(),
                    Math.abs(expected * solver.getRelativeAccuracy()));
        result = solver.solve(f, min, max);
        assertEquals(expected, result, tolerance);
    }

    /**
     * Test of solver for the quadratic function.
     */
    public void testQuadraticFunction() throws MathException {
        double min, max, expected, result, tolerance;

        // p(x) = 2x^2 + 5x - 3 = (x+3)(2x-1)
        double coefficients[] = { -3.0, 5.0, 2.0 };
        PolynomialFunction f = new PolynomialFunction(coefficients);
        UnivariateRealSolver solver = new LaguerreSolver();

        min = 0.0; max = 2.0; expected = 0.5;
        tolerance = Math.max(solver.getAbsoluteAccuracy(),
                    Math.abs(expected * solver.getRelativeAccuracy()));
        result = solver.solve(f, min, max);
        assertEquals(expected, result, tolerance);

        min = -4.0; max = -1.0; expected = -3.0;
        tolerance = Math.max(solver.getAbsoluteAccuracy(),
                    Math.abs(expected * solver.getRelativeAccuracy()));
        result = solver.solve(f, min, max);
        assertEquals(expected, result, tolerance);
    }

    /**
     * Test of solver for the quintic function.
     */
    public void testQuinticFunction() throws MathException {
        double min, max, expected, result, tolerance;

        // p(x) = x^5 - x^4 - 12x^3 + x^2 - x - 12 = (x+1)(x+3)(x-4)(x^2-x+1)
        double coefficients[] = { -12.0, -1.0, 1.0, -12.0, -1.0, 1.0 };
        PolynomialFunction f = new PolynomialFunction(coefficients);
        UnivariateRealSolver solver = new LaguerreSolver();

        min = -2.0; max = 2.0; expected = -1.0;
        tolerance = Math.max(solver.getAbsoluteAccuracy(),
                    Math.abs(expected * solver.getRelativeAccuracy()));
        result = solver.solve(f, min, max);
        assertEquals(expected, result, tolerance);

        min = -5.0; max = -2.5; expected = -3.0;
        tolerance = Math.max(solver.getAbsoluteAccuracy(),
                    Math.abs(expected * solver.getRelativeAccuracy()));
        result = solver.solve(f, min, max);
        assertEquals(expected, result, tolerance);

        min = 3.0; max = 6.0; expected = 4.0;
        tolerance = Math.max(solver.getAbsoluteAccuracy(),
                    Math.abs(expected * solver.getRelativeAccuracy()));
        result = solver.solve(f, min, max);
        assertEquals(expected, result, tolerance);
    }

    /**
     * Test of solver for the quintic function using solveAll().
     */
    public void testQuinticFunction2() throws MathException {
        double initial = 0.0, tolerance;
        Complex expected, result[];

        // p(x) = x^5 + 4x^3 + x^2 + 4 = (x+1)(x^2-x+1)(x^2+4)
        double coefficients[] = { 4.0, 0.0, 1.0, 4.0, 0.0, 1.0 };
        LaguerreSolver solver = new LaguerreSolver();
        result = solver.solveAll(coefficients, initial);

        expected = new Complex(0.0, -2.0);
        tolerance = Math.max(solver.getAbsoluteAccuracy(),
                    Math.abs(expected.abs() * solver.getRelativeAccuracy()));
        TestUtils.assertContains(result, expected, tolerance);

        expected = new Complex(0.0, 2.0);
        tolerance = Math.max(solver.getAbsoluteAccuracy(),
                    Math.abs(expected.abs() * solver.getRelativeAccuracy()));
        TestUtils.assertContains(result, expected, tolerance);

        expected = new Complex(0.5, 0.5 * Math.sqrt(3.0));
        tolerance = Math.max(solver.getAbsoluteAccuracy(),
                    Math.abs(expected.abs() * solver.getRelativeAccuracy()));
        TestUtils.assertContains(result, expected, tolerance);

        expected = new Complex(-1.0, 0.0);
        tolerance = Math.max(solver.getAbsoluteAccuracy(),
                    Math.abs(expected.abs() * solver.getRelativeAccuracy()));
        TestUtils.assertContains(result, expected, tolerance);

        expected = new Complex(0.5, -0.5 * Math.sqrt(3.0));
        tolerance = Math.max(solver.getAbsoluteAccuracy(),
                    Math.abs(expected.abs() * solver.getRelativeAccuracy()));
        TestUtils.assertContains(result, expected, tolerance);
    }

    /**
     * Test of parameters for the solver.
     */
    public void testParameters() throws Exception {
        double coefficients[] = { -3.0, 5.0, 2.0 };
        PolynomialFunction f = new PolynomialFunction(coefficients);
        UnivariateRealSolver solver = new LaguerreSolver();

        try {
            // bad interval
            solver.solve(f, 1, -1);
            fail("Expecting IllegalArgumentException - bad interval");
        } catch (IllegalArgumentException ex) {
            // expected
        }
        try {
            // no bracketing
            solver.solve(f, 2, 3);
            fail("Expecting IllegalArgumentException - no bracketing");
        } catch (IllegalArgumentException ex) {
            // expected
        }
        try {
            // bad function
            solver.solve(new SinFunction(), -1, 1);
            fail("Expecting IllegalArgumentException - bad function");
        } catch (IllegalArgumentException ex) {
            // expected
        }
    }
}