import java.math.BigDecimal;

/**
 * @author DevDio, created on 09.09.2017.
 */
class CustomMath {

    /**
     * Bigger border number = bigger PI precision
     * AND longer run time because of calculations
     */
    private static final long COUNTER_BORDER = 10_000_000;

    private static boolean DEBUG = true;

    /**
     * Calculates PI number up until loop
     * reaches COUNTER_BORDER
     *
     * @return PI number of primitive double type
     */
    public static double getPi() {

        double pi = 0;

        long start = System.currentTimeMillis();

        // calculate PI number loop
        for(int i = 0; i < COUNTER_BORDER; i++) {
            pi += 4*((Math.pow(-1, i)) / (2*i + 1));
        }

        long end = System.currentTimeMillis();

        if(DEBUG) {
            System.out.println("Run time: " + (end - start) + " ms");
        }

        return pi;
    }

    /**
     * Calculates PI number up until loop
     * reaches COUNTER_BORDER
     *
     * @return PI number of BigDecimal type
     */
    public static BigDecimal getPiAsBigDecimal() {

        BigDecimal pi = BigDecimal.ZERO;

        long start = System.currentTimeMillis();

        // calculate PI number loop
        for(int i = 0; i < COUNTER_BORDER; i++) {
            double pow = Math.pow(-1, i);
            int i1 = (2 * i) + 1;
            double i2 = 4 * (pow / i1);
            pi = pi.add(new BigDecimal(i2)); // is new object creation really necessary?
        }

        long end = System.currentTimeMillis();

        if(DEBUG) {
            System.out.println("Run time: " + (end - start) + " ms");
        }

        return pi;
    }
}

public class Client {

    public static void main(String[] args) {

        System.out.println("Internal: ");
        System.out.println("PI: " + Math.PI);
        System.out.println("With primitives: ");
        System.out.println("PI: " + CustomMath.getPi());
        System.out.println("With objects: ");
        System.out.println("PI: " + CustomMath.getPiAsBigDecimal());
    }
}