/**

* Write a program called ComputePI to compute the value of π,

* using the following series expansion. You have to decide on the termination

* criterion used in the computation (such as the number of terms used

* or the magnitude of an additional term).

*

* PI = 4 * (1 -1/3 + 1/5 - 1/7 + 1/9 - 1/11 + 1/13 - 1/15 ...)

*/

package javaexercises.flowcontrol;

/**

*

* @author User

*/

public class ComputePI {

public static void main(String[] args) {

double precision = 0.0000001;

ComputePI aComputePI = new ComputePI();

double pi = aComputePI.getPI(precision);

System.out.printf("Difference between the values obtained and the Math.PI: %.10f \n", (double)(Math.PI - pi));

}

/**

* Compute PI value with precision.

*

* @param double precision

* @return double

*/

private double getPI(double precision) {

double sumOld;

double sumNew = 0.0;

long i = 0;

do {

sumOld = sumNew;

sumNew += ((i % 2 == 0) ? 1 : -1) * (double) 4/(2*i + 1);

++i;

} while( (double) Math.abs(sumNew - sumOld) >= precision);

System.out.printf("Calculated items %d, PI = %.10f", i, sumOld);

System.out.println();

return sumOld;

}

}