Java stddev stddev(final int[] scores)

Description

stddev

License

Apache License

Declaration

public static float stddev(final int[] scores) 

Method Source Code

//package com.java2s;
/*/*  w  w  w. j  a  v a2  s .c om*/
 * @(#)$Id$
 *
 * Copyright 2006-2008 Makoto YUI
 *
 * 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.
 * 
 * Contributors:
 *     Makoto YUI - initial implementation
 */

public class Main {
    public static float stddev(final int[] scores) {
        if (scores.length == 0) {
            return 0f;
        }
        final float v = variance(scores);
        return (float) Math.sqrt(v);
    }

    public static double stddev(final long[] scores) {
        if (scores.length == 0) {
            return 0f;
        }
        final double v = variance(scores);
        return Math.sqrt(v);
    }

    public static float variance(final int[] scores) {
        if (scores.length == 0) {
            return 0f;
        }
        final float mean = mean(scores);
        float variance = 0f;
        for (int s : scores) {
            float deviation = s - mean;
            variance += (deviation * deviation);
        }
        return variance / (scores.length - 1);
    }

    public static double variance(final long[] scores) {
        if (scores.length == 0) {
            return 0d;
        }
        final double mean = mean(scores);
        double variance = 0f;
        for (long s : scores) {
            double deviation = s - mean;
            variance += (deviation * deviation);
        }
        return variance / (scores.length - 1);
    }

    public static float mean(final int[] scores) {
        if (scores.length == 0) {
            return -1f;
        }
        long total = 0L;
        for (int s : scores) {
            total += s;
        }
        return total / scores.length;
    }

    public static double mean(final long[] scores) {
        if (scores.length == 0) {
            return -1d;
        }
        long total = 0L;
        for (long s : scores) {
            total += s;
        }
        return total / scores.length;
    }
}

Related

1. stddev(double[] arr)
2. stdDev(double[] array)
3. stdDev(double[] data)
4. stddev(double[] observations)
5. stddev(final double[] in, final int start, final int length)
6. stddev(float[] data)
7. stddev(int[] values, int start, int length)
8. stdDev(Integer[] values)
9. stddev(long[] samples)