Java Variance variance(double[] population)

Description

variance

License

Apache License

Declaration

public static double variance(double[] population) 

Method Source Code

//package com.java2s;
/*******************************************************************************
 * The ABAMS project//from  ww  w .  ja  v  a 2s .  co m
 * 
 * Copyright (c) 2012 University of British Columbia
 * 
 * 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.
 ******************************************************************************/

public class Main {
    public static double variance(double[] population) {
        long n = 0;
        double mean = 0;
        double s = 0.0;

        for (double x : population) {
            n++;
            double delta = x - mean;
            mean += delta / n;
            s += delta * (x - mean);
        }
        // if you want to calculate std deviation
        // of a sample change this to (s/(n-1))
        return (s / n);
    }
}

Related

1. variance(double[] arr)
2. variance(double[] array)
3. variance(double[] array)
4. variance(double[] d)
5. Variance(double[] in, double mean)
6. variance(double[] v)
7. variance(double[] vals)
8. variance(double[] values)
9. variance(double[] values, boolean isUnbiased)