/* An actor that outputs a random sequence with a NegativeBinomial distribution.
Copyright (c) 2004-2006 The Regents of the University of California.
All rights reserved.
Permission is hereby granted, without written agreement and without
license or royalty fees, to use, copy, modify, and distribute this
software and its documentation for any purpose, provided that the above
copyright notice and the following two paragraphs appear in all copies
of this software.
IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE
PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF
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ENHANCEMENTS, OR MODIFICATIONS.
PT_COPYRIGHT_VERSION_2
COPYRIGHTENDKEY
*/
package ptolemy.actor.lib.colt;
import ptolemy.actor.parameters.PortParameter;
import ptolemy.data.BooleanToken;
import ptolemy.data.DoubleToken;
import ptolemy.data.IntToken;
import ptolemy.data.expr.SingletonParameter;
import ptolemy.data.type.BaseType;
import ptolemy.kernel.CompositeEntity;
import ptolemy.kernel.util.IllegalActionException;
import ptolemy.kernel.util.NameDuplicationException;
import cern.jet.random.NegativeBinomial;
//////////////////////////////////////////////////////////////////////////
//// NegativeBinomial
/**
Produce a random sequence with a NegativeBinomial distribution. On each
iteration, a new random number is produced. The output port is of
type DoubleToken. The values that are generated are independent
and identically distributed with the mean and the standard
deviation given by parameters. In addition, the seed can be
specified as a parameter to control the sequence that is generated.
<p> This actor instantiates a
<a href="http://hoschek.home.cern.ch/hoschek/colt/V1.0.3/doc/cern/jet/random/NegativeBinomial.html">cern.jet.random.NegativeBinomial</a> object with
n, the number of trials set to 1 and p, the probability of success, set
to 0.5.
A definition of NegativeBinomial by Wolfgang Hoschek can be found at
<a href="http://hoschek.home.cern.ch/hoschek/colt/V1.0.3/doc/cern/jet/stat/Probability.html#negativeBinomial(int,%20int,%20double)"><code>http://hoschek.home.cern.ch/hoschek/colt/V1.0.3/doc/cern/jet/stat/Probability.html#negativeBinomial(int,%20int,%20double)</code></a>:
<blockquote>
<h3>
negativeBinomial</h3>
<pre>public static double <b>negativeBinomial</b>(int k,
int n,
double p)</pre>
Returns the sum of the terms <tt>0</tt> through <tt>k</tt> of the Negative Binomial Distribution.
<pre> k
-- ( n+j-1 ) n j
> ( ) p (1-p)
-- ( j )
j=0
</pre>
In a sequence of Bernoulli trials, this is the probability
that <tt>k</tt> or fewer failures precede the <tt>n</tt>-th success.
<p>
The terms are not computed individually; instead the incomplete
beta integral is employed, according to the formula
</p><p>
<tt>y = negativeBinomial( k, n, p ) = Gamma.incompleteBeta( n, k+1, p )</tt>.
All arguments must be positive,</p>
<b>Parameters:
<br></b><code>k</code> - end term.
<br><code>n</code> - the number of trials.
<br><code>p</code> - the probability of success (must be in <tt>(0.0,1.0)</tt>).
</blockquote>
The above description of negativeBinomial() is
<a href="doc-files/colt-copyright.htm">copyrighted</a>.
@author David Bauer and Kostas Oikonomou
@version $Id$
@since Ptolemy II 4.1
@Pt.ProposedRating Red (cxh)
@Pt.AcceptedRating Red (cxh)
*/
public class ColtNegativeBinomial extends ColtRandomSource {
/** Construct an actor with the given container and name.
* @param container The container.
* @param name The name of this actor.
* @exception IllegalActionException If the actor cannot be contained
* by the proposed container.
* @exception NameDuplicationException If the container already has an
* actor with this name.
*/
public ColtNegativeBinomial(CompositeEntity container, String name)
throws NameDuplicationException, IllegalActionException {
super(container, name);
output.setTypeEquals(BaseType.INT);
n = new PortParameter(this, "n", new IntToken(1));
n.setTypeEquals(BaseType.INT);
new SingletonParameter(n.getPort(), "_showName")
.setToken(BooleanToken.TRUE);
p = new PortParameter(this, "p", new DoubleToken(0.5));
p.setTypeEquals(BaseType.DOUBLE);
new SingletonParameter(p.getPort(), "_showName")
.setToken(BooleanToken.TRUE);
p.moveToFirst();
n.moveToFirst();
}
///////////////////////////////////////////////////////////////////
//// ports and parameters ////
/** The mean, or n.
* This has type int with default value 1.
*/
public PortParameter n;
/** The variance, or p.
* This has type double with default 0.5.
*/
public PortParameter p;
///////////////////////////////////////////////////////////////////
//// public methods ////
/** Send a random number with a NegativeBinomial distribution to the output.
* This number is only changed in the prefire() method, so it will
* remain constant throughout an iteration.
* @exception IllegalActionException If there is no director.
*/
public void fire() throws IllegalActionException {
n.update();
p.update();
super.fire();
output.send(0, new IntToken(_current));
}
///////////////////////////////////////////////////////////////////
//// protected methods ////
/** Method that is called after _randomNumberGenerator is changed.
*/
protected void _createdNewRandomNumberGenerator() {
_generator = new NegativeBinomial(1, 0.5, _randomNumberGenerator);
}
/** Generate a new random number.
* @exception IllegalActionException If parameter values are incorrect.
*/
protected void _generateRandomNumber() throws IllegalActionException {
int nValue = ((IntToken) n.getToken()).intValue();
double pValue = ((DoubleToken) p.getToken()).doubleValue();
_current = _generator.nextInt(nValue, pValue);
}
///////////////////////////////////////////////////////////////////
//// private variables ////
/** The random number for the current iteration. */
private int _current;
/** The random number generator. */
private NegativeBinomial _generator;
}