/*
* Copyright (C) 2011 Jacquet Wong
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package sound.musicg.math.statistics;
/**
* Evaluate the standard deviation of an array
*
* @author Jacquet Wong
*
*/
public class StandardDeviation extends MathStatistics{
private Mean mean=new Mean();
public StandardDeviation(){
}
public StandardDeviation(double[] values){
setValues(values);
}
public double evaluate(){
mean.setValues(values);
double meanValue=mean.evaluate();
int size=values.length;
double diffSquare=0;
double sd=Double.NaN;
for (int i=0; i<size; i++){
diffSquare+=Math.pow(values[i]-meanValue,2);
}
if (size>0){
sd=Math.sqrt(diffSquare/size);
}
return sd;
}
}