Util.java Source code

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Here is the source code for Util.java

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/*
 * @(#)MathUtil.java   1.0 Apr 26, 2008
 *
 *   The MIT License
 *
 *   Copyright (c) 2008 Malachi de AElfweald <malachid@gmail.com>
 *
 *   Permission is hereby granted, free of charge, to any person obtaining a copy
 *   of this software and associated documentation files (the "Software"), to deal
 *   in the Software without restriction, including without limitation the rights
 *   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 *   copies of the Software, and to permit persons to whom the Software is
 *   furnished to do so, subject to the following conditions:
 *
 *   The above copyright notice and this permission notice shall be included in
 *   all copies or substantial portions of the Software.
 *
 *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 *   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 *   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 *   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 *   THE SOFTWARE.
 */
import java.math.BigDecimal;
import java.math.BigInteger;
import java.math.RoundingMode;

public class Util {
    protected static BigInteger BigIntegerZERO = BigInteger.ZERO;
    protected static BigInteger BigIntegerONE = BigInteger.ONE;
    protected static BigInteger BigIntegerTWO = BigInteger.valueOf(2);
    protected static BigInteger BigIntegerTHREE = BigInteger.valueOf(3);
    protected static BigInteger FactorialBreakpoint = BigInteger.valueOf(96);
    protected static BigDecimal BigDecimalZERO = BigDecimal.ZERO;
    protected static BigDecimal BigDecimalONE = BigDecimal.ONE;
    protected static BigDecimal BigDecimalTWO = new BigDecimal(2);
    protected static BigDecimal BigDecimalFOUR = new BigDecimal(4);

    public static BigDecimal[] quadratic(BigDecimal a, BigDecimal b, BigDecimal c, RoundingMode rounding) {
        // ax^2 + bx + c = 0
        BigDecimal part1 = b.negate();
        BigDecimal part2 = sqrt(b.multiply(b).subtract(BigDecimalFOUR.multiply(a).multiply(c)), rounding);
        BigDecimal part3 = BigDecimalTWO.multiply(a);
        BigDecimal[] toRet = new BigDecimal[2];
        toRet[0] = (part1.subtract(part2)).divide(part3, RoundingMode.CEILING);
        toRet[1] = (part1.add(part2)).divide(part3, RoundingMode.CEILING);
        return toRet;
    }

    public static BigInteger sqrt(BigInteger number) {
        return sqrt(number, BigIntegerONE);
    }

    public static BigDecimal sqrt(BigDecimal number, RoundingMode rounding) {
        return sqrt(number, BigDecimalONE, rounding);
    }

    protected static BigInteger sqrt(BigInteger number, BigInteger guess) {
        // ((n/g) + g)/2: until same result twice in a row
        //      BigInteger result = number.divide(guess).add(guess).divide(BigIntegerTWO);
        //      if(result.compareTo(guess) == 0)
        //         return result;
        //
        //      return sqrt(number, result);

        // redoing this to avoid StackOverFlow
        BigInteger result = BigIntegerZERO;
        BigInteger flipA = result;
        BigInteger flipB = result;
        boolean first = true;
        while (result.compareTo(guess) != 0) {
            if (!first)
                guess = result;
            else
                first = false;

            result = number.divide(guess).add(guess).divide(BigIntegerTWO);
            // handle flip flops
            if (result.equals(flipB))
                return flipA;

            flipB = flipA;
            flipA = result;
        }
        return result;

    }

    public static BigDecimal sqrt(BigDecimal number, BigDecimal guess, RoundingMode rounding) {
        BigDecimal result = BigDecimalZERO;
        BigDecimal flipA = result;
        BigDecimal flipB = result;
        boolean first = true;
        while (result.compareTo(guess) != 0) {
            if (!first)
                guess = result;
            else
                first = false;

            result = number.divide(guess, rounding).add(guess).divide(BigDecimalTWO, rounding);
            // handle flip flops
            if (result.equals(flipB))
                return flipA;

            flipB = flipA;
            flipA = result;
        }
        return result;
    }
}