com.liferay.portal.kernel.util.MathUtil.java Source code

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Here is the source code for com.liferay.portal.kernel.util.MathUtil.java

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/**
 * Copyright (c) 2000-present Liferay, Inc. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License as published by the Free
 * Software Foundation; either version 2.1 of the License, or (at your option)
 * any later version.
 *
 * This library 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 Lesser General Public License for more
 * details.
 */

package com.liferay.portal.kernel.util;

import com.liferay.portal.kernel.log.Log;
import com.liferay.portal.kernel.log.LogFactoryUtil;

import java.text.NumberFormat;

import java.util.HashMap;
import java.util.Map;

/**
 * @author Brian Wing Shun Chan
 */
public class MathUtil {

    public static int base2Log(long x) {
        return _base2LogValues.get(x);
    }

    public static long base2Pow(int x) {
        if (x == 0) {
            return 1;
        }

        return 2L << (x - 1);
    }

    public static int difference(Integer value1, Integer value2) {
        return value1 - value2;
    }

    public static int factorial(int x) {
        if (x < 0) {
            return 0;
        }

        int factorial = 1;

        while (x > 1) {
            factorial = factorial * x;
            x = x - 1;
        }

        return factorial;
    }

    public static double format(double x, int max, int min) {
        NumberFormat nf = NumberFormat.getInstance();

        nf.setMaximumFractionDigits(max);
        nf.setMinimumFractionDigits(min);

        try {
            Number number = nf.parse(nf.format(x));

            x = number.doubleValue();
        } catch (Exception e) {
            _log.error(e.getMessage());
        }

        return x;
    }

    public static int[] generatePrimes(int max) {
        if (max < 2) {
            return new int[0];
        }

        boolean[] crossedOut = new boolean[max + 1];

        for (int i = 2; i < crossedOut.length; i++) {
            crossedOut[i] = false;
        }

        int limit = (int) Math.sqrt(crossedOut.length);

        for (int i = 2; i <= limit; i++) {
            if (!crossedOut[i]) {
                for (int multiple = 2 * i; multiple < crossedOut.length; multiple += i) {

                    crossedOut[multiple] = true;
                }
            }
        }

        int uncrossedCount = 0;

        for (int i = 2; i < crossedOut.length; i++) {
            if (!crossedOut[i]) {
                uncrossedCount++;
            }
        }

        int[] result = new int[uncrossedCount];

        for (int i = 2, j = 0; i < crossedOut.length; i++) {
            if (!crossedOut[i]) {
                result[j++] = i;
            }
        }

        return result;
    }

    public static boolean isEven(int x) {
        if ((x % 2) == 0) {
            return true;
        }

        return false;
    }

    public static boolean isOdd(int x) {
        return !isEven(x);
    }

    public static double product(Double... values) {
        double product = 1.0;

        for (double value : values) {
            product *= value;
        }

        return product;
    }

    public static int product(Integer... values) {
        int product = 1;

        for (int value : values) {
            product *= value;
        }

        return product;
    }

    public static long product(Long... values) {
        long product = 1;

        for (long value : values) {
            product *= value;
        }

        return product;
    }

    public static int quotient(Integer value1, Integer value2) {
        return value1 / value2;
    }

    public static double sum(Double... values) {
        double sum = 0.0;

        for (double value : values) {
            sum += value;
        }

        return sum;
    }

    public static int sum(Integer... values) {
        int sum = 0;

        for (int value : values) {
            sum += value;
        }

        return sum;
    }

    public static long sum(Long... values) {
        long sum = 0;

        for (long value : values) {
            sum += value;
        }

        return sum;
    }

    private static final Log _log = LogFactoryUtil.getLog(MathUtil.class);

    private static final Map<Long, Integer> _base2LogValues = new HashMap<Long, Integer>() {
        {
            put(0L, Integer.MIN_VALUE);

            for (int i = 0; i < 63; i++) {
                put(base2Pow(i), i);
            }
        }
    };

}