Apache
/
commons-math
mirror of https://github.com/apache/commons-math.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Improved javadoc, implementation. 

git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/math/trunk@141316 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Phil Steitz 2004-06-18 07:03:40 +00:00
parent 0b501b4ac6
commit e90f31a26c
1 changed files with 20 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
src/java/org/apache/commons/math/stat/univariate/moment/GeometricMean.java
View File

@ -21,23 +21,30 @@ 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
* @version $Revision: 1.18 $ $Date: 2004/04/27 16:42:30 $
* geometric mean </a> of the available values.
* <p>
* Uses {@link SumOfLogs} superclass 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 both <code>Double.POSITIVE_INFINITY</code> and
* <code>Double.NEGATIVE_INFINITY</code> are among the values, the result is
* <code>NaN.</code></li>
* </ul>
*
*
* @version $Revision: 1.19 $ $Date: 2004/06/18 07:03:40 $
*/
public class GeometricMean extends SumOfLogs implements Serializable{
/** Serializable version identifier */
static final long serialVersionUID = -8178734905303459453L;
/** */
/**Number of values that have been added */
protected long n = 0;
/** */
private double geoMean = Double.NaN;
/** */
private double lastSum = 0.0;
/**
* @see org.apache.commons.math.stat.univariate.StorelessUnivariateStatistic#increment(double)
*/
@ -50,11 +57,11 @@ public class GeometricMean extends SumOfLogs implements Serializable{
* @see org.apache.commons.math.stat.univariate.StorelessUnivariateStatistic#getResult()
*/
public double getResult() {
if (lastSum != super.getResult() || n == 1) {
lastSum = super.getResult();
geoMean = Math.exp(lastSum / (double) n);
if (n > 0) {
return Math.exp(super.getResult() / (double) n);
} else {
return Double.NaN;
}
return geoMean;
}
/**
@ -62,8 +69,6 @@ public class GeometricMean extends SumOfLogs implements Serializable{
*/
public void clear() {
super.clear();
lastSum = 0.0;
geoMean = Double.NaN;
n = 0;
}