import java.math.BigDecimal;/** * Computes the sum of the series 1 - 1/2 + 1/4 - 1/6 + 1/8 etc. Demonstrates * the use of {@link java.math.BigDecimal} in order to achieve high precision * floating point numbers. * * @author Tim De Pauw */public class BigDecTest { /** * Size of the series. */ public final static int SIZE = 1000000; /** * Number of digits to the right of the decimal point. */ public final static int SCALE = 50; /** * Auxiliary constant. A {@link java.math.BigDecimal} representing the * number two. */ public final static BigDecimal TWO = new BigDecimal(2); /** * Auxiliary constant. A {@link java.math.BigDecimal} representing the * number one. */ public final static BigDecimal ONE = new BigDecimal(1); /** * Auxiliary constant. A {@link java.math.BigDecimal} representing the * number negative one. */ public final static BigDecimal NEG_ONE = new BigDecimal(-1); public static void main (String[] args) { System.out.println("Size: " + SIZE); System.out.println("Scale: " + SCALE); BigDecimal sum = ONE; long start = System.currentTimeMillis(); for (int i = 1; i < SIZE; i++) sum = sum.add((i % 2 == 0 ? ONE : NEG_ONE) .divide(TWO.multiply(new BigDecimal(i)), SCALE, BigDecimal.ROUND_HALF_UP)); long end = System.currentTimeMillis(); System.out.println("Result: " + sum); System.out.println("Time: " + (end - start) / 1000.0 + " seconds"); }}