BigDecimal the Babylonian square root method (Newton's method) - Java java.math

Java examples for java.math:BigDecimal

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Description

BigDecimal the Babylonian square root method (Newton's method)

Demo Code


//package com.java2s;
import java.math.BigDecimal;

import static java.math.RoundingMode.HALF_UP;

public class Main {
    public static void main(String[] argv) throws Exception {
        BigDecimal A = new BigDecimal("1234");
        int SCALE = 2;
        System.out.println(sqrt(A, SCALE));
    }//from w  w  w. j a va  2 s  . c  o m

    public static final BigDecimal TWO = BigDecimal.valueOf(2);

    /**
     * the Babylonian square root method (Newton's method)
     *
     * @param A
     * @param SCALE
     * @return
     */
    public static BigDecimal sqrt(BigDecimal A, final int SCALE) {
        BigDecimal x0 = new BigDecimal("0");
        BigDecimal x1 = new BigDecimal(Math.sqrt(A.doubleValue()));

        while (!x0.equals(x1)) {
            x0 = x1;
            x1 = A.divide(x0, SCALE, HALF_UP);
            x1 = x1.add(x0);
            x1 = x1.divide(TWO, SCALE, HALF_UP);
        }

        return x1;
    }
}

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