I'm crafting code to implement this algorithm:
However, I'm getting this error, even with MathContext(1000):
Exception in thread "main" java.lang.ArithmeticException: Non-terminating decimal expansion; no exact representable decimal result.
at java.math.BigDecimal.divide(BigDecimal.java:1603)
at picalculator.PiCalculator.calculatePi(PiCalculator.java:59)
at picalculator.PiCalculator.main(PiCalculator.java:25)
Java Result: 1
While using this method:
public static void calculatePi() {
BigInteger firstFactorial;
BigInteger secondFactorial;
BigInteger firstMultiplication;
BigInteger firstExponent;
BigInteger secondExponent;
int firstNumber = 1103;
BigInteger firstAddition;
BigDecimal currentPi = BigDecimal.ONE;
BigDecimal pi = BigDecimal.ONE;
BigDecimal one = BigDecimal.ONE;
int secondNumber = 2;
double thirdNumber = Math.sqrt(2.0);
int fourthNumber = 9801;
BigDecimal prefix = BigDecimal.ONE;
for(int i=1;i<4;i++){
firstFactorial = factorial(4*i);
secondFactorial = factorial(i);
firstMultiplication = BigInteger.valueOf(26390*i);
firstExponent = exponent(secondFactorial, 4);
secondExponent = exponent(BigInteger.valueOf(396),4*i);
firstAddition = BigInteger.valueOf(firstNumber).add(firstMultiplication);
currentPi = currentPi.add(new BigDecimal(firstFactorial.multiply(firstAddition)).divide(new BigDecimal(firstExponent.multiply(secondExponent)), new MathContext(10000)));
}
prefix =new BigDecimal(secondNumber*thirdNumber);
prefix = prefix.divide(new BigDecimal(fourthNumber), new MathContext(1000));
currentPi = currentPi.multiply(prefix, new MathContext(1000));
pi = one.divide(currentPi);
System.out.println("Pi is: " + pi);
return;
}
I have proven that factorial(a); and exponent(a,b) return the factorial of a and the result of a^b respectively, accurately.
Does anyone know how to fix this?
You need
pi = one.divide(currentPi, new MathContext(1000));
Since the result is almost certainly a repeating decimal.
Consider
BigDecimal a = new BigDecimal("4");
BigDecimal b = new BigDecimal("3");
BigDecimal c = a.divide(b) // java.lang.ArithmeticException: Non-terminating decimal expansion
BigDecimal c = a.divide(b, new MathContext(10)); // No exception
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