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Changed implementation to wrap, rather than extend SumOfLogs. 

git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/math/trunk@141394 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Phil Steitz 2004-07-18 04:37:08 +00:00
parent 8c57bad833
commit a94d386979
1 changed files with 30 additions and 20 deletions
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50
src/java/org/apache/commons/math/stat/univariate/moment/GeometricMean.java
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@ -15,20 +15,20 @@
*/
package org.apache.commons.math.stat.univariate.moment;
import java.io.Serializable;
import org.apache.commons.math.stat.univariate.AbstractStorelessUnivariateStatistic;
import org.apache.commons.math.stat.univariate.summary.SumOfLogs;
/**
* Returns the <a href="http://www.xycoon.com/geometric_mean.htm">
* geometric mean </a> of the available values.
* <p>
* Uses {@link SumOfLogs} superclass to compute sum of logs and returns
* Uses a {@link SumOfLogs} instance to compute sum of logs and returns
* <code> exp( 1/n (sum of logs) ).</code> Therefore,
* <ul>
* <li>If any of values are < 0, the result is <code>NaN.</code></li>
* <li>If all values are non-negative and less than <code>Double.POSITIVE_INFINITY</code>,
* but at least one value is 0, the result is <code>0.</code></li>
* <li>If all values are non-negative and less than
* <code>Double.POSITIVE_INFINITY</code>, but at least one value is 0, the
* result is <code>0.</code></li>
* <li>If both <code>Double.POSITIVE_INFINITY</code> and
* <code>Double.NEGATIVE_INFINITY</code> are among the values, the result is
* <code>NaN.</code></li>
@ -40,30 +40,36 @@ import org.apache.commons.math.stat.univariate.summary.SumOfLogs;
* <code>clear()</code> method, it must be synchronized externally.
*
*
* @version $Revision: 1.21 $ $Date: 2004/07/04 09:02:36 $
* @version $Revision: 1.22 $ $Date: 2004/07/18 04:37:08 $
*/
public class GeometricMean extends SumOfLogs implements Serializable{
public class GeometricMean extends AbstractStorelessUnivariateStatistic {
/** Serializable version identifier */
static final long serialVersionUID = -8178734905303459453L;
/**Number of values that have been added */
protected long n = 0;
/** Wrapped SumOfLogs instance */
private SumOfLogs sumOfLogs;
/**
* Create a GeometricMean instance
*/
public GeometricMean() {
sumOfLogs = new SumOfLogs();
}
/**
* @see org.apache.commons.math.stat.univariate.StorelessUnivariateStatistic#increment(double)
*/
public void increment(final double d) {
n++;
super.increment(d);
sumOfLogs.increment(d);
}
/**
* @see org.apache.commons.math.stat.univariate.StorelessUnivariateStatistic#getResult()
*/
public double getResult() {
if (n > 0) {
return Math.exp(super.getResult() / (double) n);
if (sumOfLogs.getN() > 0) {
return Math.exp(sumOfLogs.getResult() / (double) sumOfLogs.getN());
} else {
return Double.NaN;
}
@ -73,8 +79,7 @@ public class GeometricMean extends SumOfLogs implements Serializable{
* @see org.apache.commons.math.stat.univariate.StorelessUnivariateStatistic#clear()
*/
public void clear() {
super.clear();
n = 0;
sumOfLogs.clear();
}
/**
@ -94,11 +99,16 @@ public class GeometricMean extends SumOfLogs implements Serializable{
* index parameters are not valid
*/
public double evaluate(
final double[] values,
final int begin,
final int length) {
final double[] values, final int begin, final int length) {
return Math.exp(
super.evaluate(values, begin, length) / (double) length);
sumOfLogs.evaluate(values, begin, length) / (double) length);
}
/**
* @see org.apache.commons.math.stat.univariate.StorelessUnivariateStatistic#getN()
*/
public long getN() {
return sumOfLogs.getN();
}
}