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

Addition of sumLog method (natural) to get the sum of the Logs. Altered GeometricMean to calculate the geometricMean from the sum of logs. 

git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/math/trunk@140920 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Mark R. Diggory 2003-06-18 01:56:03 +00:00
parent d4f6a5c818
commit 374b62d120
1 changed files with 20 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
src/java/org/apache/commons/math/stat/StatUtils.java
View File

@ -92,7 +92,7 @@ public class StatUtils {
* Returns the product for this collection of values * Returns the product for this collection of values
* @param values Is a double[] containing the values * @param values Is a double[] containing the values
* @return the product values or Double.NaN if the array is empty * @return the product values or Double.NaN if the array is empty
*/ */
public static double product(double[] values) { public static double product(double[] values) {
double product = Double.NaN; double product = Double.NaN;
if( values.length > 0 ) { if( values.length > 0 ) {
@ -104,6 +104,22 @@ public class StatUtils {
return product; return product;
} }
/**
* Returns the sum of the natural logs for this collection of values
* @param values Is a double[] containing the values
* @return the sumLog value or Double.NaN if the array is empty
*/
public static double sumLog(double[] values) {
double sumLog = Double.NaN;
if( values.length > 0 ) {
sumLog = 0.0;
for( int i = 0; i < values.length; i++) {
sumLog += Math.log(values[i]);
}
}
return sumLog;
}
/** /**
* Returns the geometric mean for this collection of values * Returns the geometric mean for this collection of values
* @param values Is a double[] containing the values * @param values Is a double[] containing the values
@ -111,7 +127,7 @@ public class StatUtils {
* any of the values are &lt;= 0. * any of the values are &lt;= 0.
*/ */
public static double geometricMean(double[] values) { public static double geometricMean(double[] values) {
return Math.pow(product(values),(1.0/values.length)); return Math.exp(sumLog(values) / (double)values.length);
} }
/** /**
@ -121,7 +137,7 @@ public class StatUtils {
* @return the mean of the values or Double.NaN if the array is empty * @return the mean of the values or Double.NaN if the array is empty
*/ */
public static double mean(double[] values) { public static double mean(double[] values) {
return sum(values) / values.length; return sum(values) / (double)values.length;
} }
/** /**
@ -155,7 +171,7 @@ public class StatUtils {
for (int i = 0; i < values.length; i++) { for (int i = 0; i < values.length; i++) {
accum += Math.pow((values[i] - mean), 2.0); accum += Math.pow((values[i] - mean), 2.0);
} }
variance = accum / (values.length - 1); variance = accum / (double)(values.length - 1);
} }
return variance; return variance;
} }