/*
 * 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.analysis.Expm1Function;
import org.apache.commons.math.analysis.QuinticFunction;
import org.apache.commons.math.analysis.SinFunction;
import org.apache.commons.math.analysis.UnivariateRealFunction;

import junit.framework.TestCase;

/**
 * Testcase for Ridders solver.
 * <p>
 * Ridders' method converges superlinearly, more specific, its rate of
 * convergence is sqrt(2). Test runs show that for a default absolute accuracy
 * of 1E-6, it generally takes less than 5 iterations for close initial bracket
 * and 5 to 10 iterations for distant initial bracket to converge.
 * 
 * @version $Revision$ $Date$
 */
public final class RiddersSolverTest extends TestCase {

	/**
	 * Test the deprecated APIs.
	 */
	@Deprecated
	public void testDeprecated() throws MathException {
		UnivariateRealFunction f = new SinFunction();
		UnivariateRealSolver solver = new RiddersSolver(f);
		double min, max, expected, result, tolerance;

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

		min = -1.0;
		max = 1.5;
		expected = 0.0;
		tolerance = Math.max(solver.getAbsoluteAccuracy(), Math.abs(expected * solver.getRelativeAccuracy()));
		result = solver.solve(min, max);
		assertEquals(expected, result, tolerance);
	}

	/**
	 * Test of solver for the sine function.
	 */
	public void testSinFunction() throws MathException {
		UnivariateRealFunction f = new SinFunction();
		UnivariateRealSolver solver = new RiddersSolver();
		double min, max, expected, result, tolerance;

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

		min = -1.0;
		max = 1.5;
		expected = 0.0;
		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 {
		UnivariateRealFunction f = new QuinticFunction();
		UnivariateRealSolver solver = new RiddersSolver();
		double min, max, expected, result, tolerance;

		min = -0.4;
		max = 0.2;
		expected = 0.0;
		tolerance = Math.max(solver.getAbsoluteAccuracy(), Math.abs(expected * solver.getRelativeAccuracy()));
		result = solver.solve(f, min, max);
		assertEquals(expected, result, tolerance);

		min = 0.75;
		max = 1.5;
		expected = 1.0;
		tolerance = Math.max(solver.getAbsoluteAccuracy(), Math.abs(expected * solver.getRelativeAccuracy()));
		result = solver.solve(f, min, max);
		assertEquals(expected, result, tolerance);

		min = -0.9;
		max = -0.2;
		expected = -0.5;
		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 exponential function.
	 */
	public void testExpm1Function() throws MathException {
		UnivariateRealFunction f = new Expm1Function();
		UnivariateRealSolver solver = new RiddersSolver();
		double min, max, expected, result, tolerance;

		min = -1.0;
		max = 2.0;
		expected = 0.0;
		tolerance = Math.max(solver.getAbsoluteAccuracy(), Math.abs(expected * solver.getRelativeAccuracy()));
		result = solver.solve(f, min, max);
		assertEquals(expected, result, tolerance);

		min = -20.0;
		max = 10.0;
		expected = 0.0;
		tolerance = Math.max(solver.getAbsoluteAccuracy(), Math.abs(expected * solver.getRelativeAccuracy()));
		result = solver.solve(f, min, max);
		assertEquals(expected, result, tolerance);

		min = -50.0;
		max = 100.0;
		expected = 0.0;
		tolerance = Math.max(solver.getAbsoluteAccuracy(), Math.abs(expected * solver.getRelativeAccuracy()));
		result = solver.solve(f, min, max);
		assertEquals(expected, result, tolerance);
	}

	/**
	 * Test of parameters for the solver.
	 */
	public void testParameters() throws Exception {
		UnivariateRealFunction f = new SinFunction();
		UnivariateRealSolver solver = new RiddersSolver();

		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
		}
	}
}
