001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.math.distribution;
018
019 /**
020 * The Chi-Squared Distribution.
021 *
022 * <p>
023 * References:
024 * <ul>
025 * <li><a href="http://mathworld.wolfram.com/Chi-SquaredDistribution.html">
026 * Chi-Squared Distribution</a></li>
027 * </ul>
028 * </p>
029 *
030 * @version $Revision: 693598 $ $Date: 2008-09-09 16:37:08 -0400 (Tue, 09 Sep 2008) $
031 */
032 public interface ChiSquaredDistribution extends ContinuousDistribution, HasDensity<Double> {
033 /**
034 * Modify the degrees of freedom.
035 * @param degreesOfFreedom the new degrees of freedom.
036 */
037 void setDegreesOfFreedom(double degreesOfFreedom);
038
039 /**
040 * Access the degrees of freedom.
041 * @return the degrees of freedom.
042 */
043 double getDegreesOfFreedom();
044
045 /**
046 * Return the probability density for a particular point.
047 * @param x The point at which the density should be computed.
048 * @return The pdf at point x.
049 */
050 double density(Double x);
051 }