    1   /*
    2    * Copyright 2003-2004 The Apache Software Foundation.
    3    *
    4    * Licensed under the Apache License, Version 2.0 (the "License");
    5    * you may not use this file except in compliance with the License.
    6    * You may obtain a copy of the License at
    7    *
    8    *      http://www.apache.org/licenses/LICENSE-2.0
    9    *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS,
    12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13   * See the License for the specific language governing permissions and
    14   * limitations under the License.
    15   */
    16  package org.apache.commons.math.special;
    17
    18  import org.apache.commons.math.MathException;
    19  import org.apache.commons.math.TestUtils;
    20
    21  import junit.framework.TestCase;
    22
    23  /***
    24   * @version $Revision: 1.10 $ $Date: 2004/06/07 20:30:16 $
    25   */
    26  public class GammaTest extends TestCase {
    27      /***
    28       * Constructor for BetaTest.
    29       * @param name
    30       */
    31      public GammaTest(String name) {
    32          super(name);
    33      }
    34
    35      private void testRegularizedGamma(double expected, double a, double x) {
    36          try {
    37              double actualP = Gamma.regularizedGammaP(a, x);
    38              double actualQ = Gamma.regularizedGammaQ(a, x);
    39              TestUtils.assertEquals(expected, actualP, 10e-5);
    40              TestUtils.assertEquals(actualP, 1.0 - actualQ, 10e-5);
    41          } catch(MathException ex){
    42              fail(ex.getMessage());
    43          }
    44      }
    45
    46      private void testLogGamma(double expected, double x) {
    47          double actual = Gamma.logGamma(x);
    48          TestUtils.assertEquals(expected, actual, 10e-5);
    49      }
    50
    51      public void testRegularizedGammaNanPositive() {
    52          testRegularizedGamma(Double.NaN, Double.NaN, 1.0);
    53      }
    54
    55      public void testRegularizedGammaPositiveNan() {
    56          testRegularizedGamma(Double.NaN, 1.0, Double.NaN);
    57      }
    58
    59      public void testRegularizedGammaNegativePositive() {
    60          testRegularizedGamma(Double.NaN, -1.5, 1.0);
    61      }
    62
    63      public void testRegularizedGammaPositiveNegative() {
    64          testRegularizedGamma(Double.NaN, 1.0, -1.0);
    65      }
    66
    67      public void testRegularizedGammaZeroPositive() {
    68          testRegularizedGamma(Double.NaN, 0.0, 1.0);
    69      }
    70
    71      public void testRegularizedGammaPositiveZero() {
    72          testRegularizedGamma(0.0, 1.0, 0.0);
    73      }
    74
    75      public void testRegularizedGammaPositivePositive() {
    76          testRegularizedGamma(0.632121, 1.0, 1.0);
    77      }
    78
    79      public void testLogGammaNan() {
    80          testLogGamma(Double.NaN, Double.NaN);
    81      }
    82
    83      public void testLogGammaNegative() {
    84          testLogGamma(Double.NaN, -1.0);
    85      }
    86
    87      public void testLogGammaZero() {
    88          testLogGamma(Double.NaN, 0.0);
    89      }
    90
    91      public void testLogGammaPositive() {
    92          testLogGamma(0.693147, 3.0);
    93      }
    94  }