src/mantissa/tests-src/org/spaceroots/mantissa/roots/BrentSolverTest.java

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package org.spaceroots.mantissa.roots;

import org.spaceroots.mantissa.functions.FunctionException;

import junit.framework.*;

public class BrentSolverTest
  extends TestCase {

  public BrentSolverTest(String name) {
    super(name);
  }

  public void testAlefeldPotraShi()
  throws FunctionException {

    TestProblem[] problems = TestProblem.getAPSProblems();
    BrentSolver solver     = new BrentSolver();

    for (int i = 0; i < problems.length; ++i) {
      TestProblem p = problems[i];
      double tol = 1.0e-10 * Math.abs(p.getExpectedRoot());
      assertTrue(solver.findRoot(p, new Checker(tol), 1000,
                                 p.getA(), p.valueAt(p.getA()),
                                 p.getB(), p.valueAt(p.getB())));
      assertTrue(p.checkResult(solver.getRoot(), tol));
    }

  }

  private static class Checker implements ConvergenceChecker {

    private double tolerance;

    public Checker (double tolerance) {
      this.tolerance = tolerance;
    }

    public int converged (double xLow, double fLow,
                          double xHigh, double fHigh) {
      return (Math.abs(xHigh - xLow) <= tolerance)
        ? ((Math.abs(fLow) <= Math.abs(fHigh))
           ? ConvergenceChecker.LOW
           : ConvergenceChecker.HIGH)
        : ConvergenceChecker.NONE;
    }

  }

  public static Test suite() {
    return new TestSuite(BrentSolverTest.class);
  }

}