Java mean meanSml(final int a, final int b)

Description

mean Sml

License

Open Source License

Return

Mean without overflow, rounded to the value of smallest magnitude (i.e. mathematical (a+b)/2, using integer division).

Declaration

public static int meanSml(final int a, final int b) 

Method Source Code

//package com.java2s;
//License from project: Open Source License 

public class Main {
    /**/*from w ww  .  j av  a 2  s  .  c  o m*/
     * @return Mean without overflow, rounded to the value of smallest magnitude (i.e. mathematical (a+b)/2, using
     *         integer division).
     */
    public static int meanSml(final int a, final int b) {
        int result = meanLow(a, b);
        if (!haveSameEvenness(a, b)) {
            // inexact
            if ((a & b) < 0 || (a | b) < 0 && a + b < 0) {
                // both < 0, or only one is < 0 and it has the largest magnitude
                result++;
            }
        }
        return result;
    }

    /**
     * @return Mean without overflow, rounded to the value of smallest magnitude (i.e. mathematical (a+b)/2, using
     *         integer division).
     */
    public static long meanSml(final long a, final long b) {
        long result = meanLow(a, b);
        if (!haveSameEvenness(a, b)) {
            // inexact
            if ((a & b) < 0 || (a | b) < 0 && a + b < 0) {
                // both < 0, or only one is < 0 and it has the largest magnitude
                result++;
            }
        }
        return result;
    }

    /**
     * @return Mean without overflow, rounded to the lowest value (i.e. mathematical floor((a+b)/2), using floating
     *         point division).
     */
    public static int meanLow(final int a, final int b) {
        return (a & b) + ((a ^ b) >> 1);
    }

    /**
     * @return Mean without overflow, rounded to the lowest value (i.e. mathematical floor((a+b)/2), using floating
     *         point division).
     */
    public static long meanLow(final long a, final long b) {
        return (a & b) + ((a ^ b) >> 1);
    }

    /**
     * @return True if the specified values are both even or both odd, false otherwise.
     */
    public static boolean haveSameEvenness(final int a, final int b) {
        return ((a ^ b) & 1) == 0;
    }

    /**
     * @return True if the specified values are both even or both odd, false otherwise.
     */
    public static boolean haveSameEvenness(final long a, final long b) {
        // faster to work on ints
        return haveSameEvenness((int) a, (int) b);
    }
}

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6. meanSquare(float[] a, int off, int length)
7. meanSquaredError(double[] x, double[] y)
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