Java Variance variance(double[] vector)

Description

Computes the variance for an array of doubles.

License

Open Source License

Parameter

Parameter	Description
vector	the array

Return

the variance

Declaration

public static double variance(double[] vector) 

Method Source Code

//package com.java2s;
/*/*  ww w  . j a va2 s .  c om*/
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

public class Main {
    /**
     * Computes the variance for an array of doubles.
     *
     * @param vector the array
     * @return the variance
     */
    public static double variance(double[] vector) {

        double sum = 0, sumSquared = 0;

        if (vector.length <= 1) {
            return 0;
        }
        for (int i = 0; i < vector.length; i++) {
            sum += vector[i];
            sumSquared += (vector[i] * vector[i]);
        }
        return (sumSquared - (sum * sum / (double) vector.length))
                / (double) (vector.length - 1);
    }
}

Related

1. variance(double[] vals)
2. variance(double[] values)
3. variance(double[] values, boolean isUnbiased)
4. variance(double[] vector)
5. variance(double[] vector)
6. variance(final double[] values)
7. variance(final double[] values, final double mean)
8. variance(final int[] scores)
9. variance(float[] v, float average)