Question

Need help with Pi Approximation on Java

Write a Java program which computes PI from the infinite series –

Ask the user how many decimal places you should compute PI to and display the number of
terms that it takes to compute PI to that many places and the approximation computed. This
formula can be used to determine when your approximation is close enough.

Math.abs(Math.PI - approx) < (0.5 * Math.pow(0.1, decimalPlaces))

Answer 1

import java.util.Scanner;

public class PiApproximation
{
public static void main(String[] args)
{
int decimalPlaces;
int terms = 1;
double approx = 0.0;
int denominator = 1;

// Scanner object to read input.
Scanner keyboard = new Scanner(System.in);

// Ask user for decimal places to
// compute PI to.
System.out.print("How many digits would you"
+ " to compute PI to? ");
decimalPlaces = keyboard.nextInt();

do
{
if (terms % 2 == 0)
{
approx = approx - (4 / denominator);
}

if (terms % 2 == 1)
{
approx = approx + (4 / denominator);
}
else
{
approx = approx + (4 / denominator);
}

denominator = denominator + 2;
terms++;
}
while (Math.abs(Math.PI - approx) < (0.5 * Math.pow(0.1, decimalPlaces)));

System.out.print("It took " + terms + " to approximate PI as "
+ approx);
}
}

Answer 2

^This is my code, the loop is the only problem I am having with the program.

Answer 3

Did you try any test output to see if it is looping or where it gets stuck? To watch values as it goes through the loop?