find the value of pi till 50 digits

Question

I want to calculate the value of PI till 50 digits.

How to do this in java for 50 decimal places?

Answer 1

public class PiReCalc {
  public static final int N = 1000; // # of terms
   public static void main(String[] args) {
  BigDecimal sum = new BigDecimal(0);      // final sum
  BigDecimal term = new BigDecimal(0);           // term without sign
  BigDecimal sign = new BigDecimal(1.0);     // sign on each term

  BigDecimal one = new BigDecimal(1.0);
  BigDecimal two = new BigDecimal(2.0);

  for (int k = 0; k < N; k++) {
     BigDecimal count = new BigDecimal(k); 
     //term = 1.0/(2.0*k + 1.0);
     BigDecimal temp1 = two.multiply(count);
     BigDecimal temp2 = temp1.add(one);
     term = one.divide(temp2,50,BigDecimal.ROUND_FLOOR);

     //sum = sum + sign*term;
     BigDecimal temp3 = sign.multiply(term);
     sum = sum.add(temp3);

     sign = sign.negate();
  }
  BigDecimal pi = new BigDecimal(0);
  BigDecimal four = new BigDecimal(4);
  pi = sum.multiply(four);

  System.out.println("Calculated pi (approx., " + N + " terms and 50 Decimal Places): " + pi);
  System.out.println("Actual pi: " + Math.PI);
   }
}

The output is

Calculated pi (approx., 1000 terms and 50 Decimal Places): 3.14059265383979292596359650286939597045138933077984
Actual pi: 3.141592653589793