001/* An actor that outputs a random sequence with a ChiSquare distribution.
002
003 Copyright (c) 2004-2016 The Regents of the University of California.
004 All rights reserved.
005 Permission is hereby granted, without written agreement and without
006 license or royalty fees, to use, copy, modify, and distribute this
007 software and its documentation for any purpose, provided that the above
008 copyright notice and the following two paragraphs appear in all copies
009 of this software.
010
011 IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
012 FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
013 ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
014 THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF
015 SUCH DAMAGE.
016
017 THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
018 INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
019 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE
020 PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF
021 CALIFORNIA HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES,
022 ENHANCEMENTS, OR MODIFICATIONS.
023
024 PT_COPYRIGHT_VERSION_2
025 COPYRIGHTENDKEY
026
027 */
028package ptolemy.actor.lib.colt;
029
030import cern.jet.random.ChiSquare;
031import ptolemy.actor.parameters.PortParameter;
032import ptolemy.data.BooleanToken;
033import ptolemy.data.DoubleToken;
034import ptolemy.data.expr.SingletonParameter;
035import ptolemy.data.type.BaseType;
036import ptolemy.kernel.CompositeEntity;
037import ptolemy.kernel.util.IllegalActionException;
038import ptolemy.kernel.util.NameDuplicationException;
039
040///////////////////////////////////////////////////////////////////
041//// ChiSquare
042
043/**
044 Produce a random sequence with a ChiSquare distribution.  On each
045 iteration, a new random number is produced.  The output port is of
046 type DoubleToken.  The values that are generated are independent
047 and identically distributed with the freedom and the standard
048 deviation given by parameters.  In addition, the seed can be
049 specified as a parameter to control the sequence that is generated.
050
051 <p> This actor instantiates a
052 <a href="http://hoschek.home.cern.ch/hoschek/colt/V1.0.3/doc/cern/jet/random/ChiSquare.html">cern.jet.random.ChiSquare</a> object with
053 freedom argument set to 1.0.
054
055 The Chi Square Distribution is
056 <blockquote>
057 A special case of the Gamma distribution.
058 <p>
059 <tt>p(x) = (1/g(f/2)) * (x/2)^(f/2-1) * exp(-x/2)</tt> with <tt>g(a)</tt> being the gamma function and <tt>f</tt> being the degrees of freedom.
060 </p><p>
061 Valid parameter ranges: <tt>freedom &gt; 0</tt>.
062 </blockquote>
063
064 The above description of Chi Square is
065 <a href="doc-files/colt-copyright.htm">copyrighted</a>.
066
067 <p>A definition of the ChiSquare distribution can be found at
068 <a href="http://www.cern.ch/RD11/rkb/AN16pp/node31.html#SECTION000310000000000000000"><code>http://www.cern.ch/RD11/rkb/AN16pp/node31.html#SECTION000310000000000000000</code></a>
069
070 @author David Bauer and Kostas Oikonomou
071 @version $Id$
072 @since Ptolemy II 4.1
073 @Pt.ProposedRating Red (cxh)
074 @Pt.AcceptedRating Red (cxh)
075 */
076public class ColtChiSquare extends ColtRandomSource {
077    /** Construct an actor with the given container and name.
078     *  @param container The container.
079     *  @param name The name of this actor.
080     *  @exception IllegalActionException If the actor cannot be contained
081     *   by the proposed container.
082     *  @exception NameDuplicationException If the container already has an
083     *   actor with this name.
084     */
085    public ColtChiSquare(CompositeEntity container, String name)
086            throws NameDuplicationException, IllegalActionException {
087        super(container, name);
088
089        output.setTypeEquals(BaseType.DOUBLE);
090
091        freedom = new PortParameter(this, "freedom", new DoubleToken(1.0));
092        freedom.setTypeEquals(BaseType.DOUBLE);
093        new SingletonParameter(freedom.getPort(), "_showName")
094                .setToken(BooleanToken.TRUE);
095
096        freedom.moveToFirst();
097    }
098
099    ///////////////////////////////////////////////////////////////////
100    ////                     ports and parameters                  ////
101
102    /** freedom.
103     *  This has type double with default value 1.0.
104     */
105    public PortParameter freedom;
106
107    ///////////////////////////////////////////////////////////////////
108    ////                         public methods                    ////
109
110    /** Send a random number with a ChiSquare distribution to the output.
111     *  This number is only changed in the prefire() method, so it will
112     *  remain constant throughout an iteration.
113     *  @exception IllegalActionException If there is no director.
114     */
115    @Override
116    public void fire() throws IllegalActionException {
117        freedom.update();
118        super.fire();
119        output.send(0, new DoubleToken(_current));
120    }
121
122    ///////////////////////////////////////////////////////////////////
123    ////                         protected methods                 ////
124
125    /** Method that is called after _randomNumberGenerator is changed.
126     */
127    @Override
128    protected void _createdNewRandomNumberGenerator() {
129        _generator = new ChiSquare(1.0, _randomNumberGenerator);
130    }
131
132    /** Generate a new random number.
133     *  @exception IllegalActionException If parameter values are incorrect.
134     */
135    @Override
136    protected void _generateRandomNumber() throws IllegalActionException {
137        double freedomValue = ((DoubleToken) freedom.getToken()).doubleValue();
138
139        _current = _generator.nextDouble(freedomValue);
140    }
141
142    ///////////////////////////////////////////////////////////////////
143    ////                         private variables                 ////
144
145    /** The random number for the current iteration. */
146    private double _current;
147
148    /** The random number generator. */
149    private ChiSquare _generator;
150}