/*
 * 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.special;

import org.apache.commons.math.MathException;
import org.apache.commons.math.TestUtils;

import junit.framework.TestCase;

/**
 * @version $Revision$ $Date$
 */
public class BetaTest extends TestCase {
	/**
	 * Constructor for BetaTest.
	 * 
	 * @param name
	 */
	public BetaTest(String name) {
		super(name);
	}

	private void testRegularizedBeta(double expected, double x, double a, double b) {
		try {
			double actual = Beta.regularizedBeta(x, a, b);
			TestUtils.assertEquals(expected, actual, 10e-15);
		} catch (MathException ex) {
			fail(ex.getMessage());
		}
	}

	private void testLogBeta(double expected, double a, double b) {
		double actual = Beta.logBeta(a, b);
		TestUtils.assertEquals(expected, actual, 10e-15);
	}

	public void testRegularizedBetaNanPositivePositive() {
		testRegularizedBeta(Double.NaN, Double.NaN, 1.0, 1.0);
	}

	public void testRegularizedBetaPositiveNanPositive() {
		testRegularizedBeta(Double.NaN, 0.5, Double.NaN, 1.0);
	}

	public void testRegularizedBetaPositivePositiveNan() {
		testRegularizedBeta(Double.NaN, 0.5, 1.0, Double.NaN);
	}

	public void testRegularizedBetaNegativePositivePositive() {
		testRegularizedBeta(Double.NaN, -0.5, 1.0, 2.0);
	}

	public void testRegularizedBetaPositiveNegativePositive() {
		testRegularizedBeta(Double.NaN, 0.5, -1.0, 2.0);
	}

	public void testRegularizedBetaPositivePositiveNegative() {
		testRegularizedBeta(Double.NaN, 0.5, 1.0, -2.0);
	}

	public void testRegularizedBetaZeroPositivePositive() {
		testRegularizedBeta(0.0, 0.0, 1.0, 2.0);
	}

	public void testRegularizedBetaPositiveZeroPositive() {
		testRegularizedBeta(Double.NaN, 0.5, 0.0, 2.0);
	}

	public void testRegularizedBetaPositivePositiveZero() {
		testRegularizedBeta(Double.NaN, 0.5, 1.0, 0.0);
	}

	public void testRegularizedBetaPositivePositivePositive() {
		testRegularizedBeta(0.75, 0.5, 1.0, 2.0);
	}

	public void testLogBetaNanPositive() {
		testLogBeta(Double.NaN, Double.NaN, 2.0);
	}

	public void testLogBetaPositiveNan() {
		testLogBeta(Double.NaN, 1.0, Double.NaN);
	}

	public void testLogBetaNegativePositive() {
		testLogBeta(Double.NaN, -1.0, 2.0);
	}

	public void testLogBetaPositiveNegative() {
		testLogBeta(Double.NaN, 1.0, -2.0);
	}

	public void testLogBetaZeroPositive() {
		testLogBeta(Double.NaN, 0.0, 2.0);
	}

	public void testLogBetaPositiveZero() {
		testLogBeta(Double.NaN, 1.0, 0.0);
	}

	public void testLogBetaPositivePositive() {
		testLogBeta(-0.693147180559945, 1.0, 2.0);
	}
}