Factorial of numbers

[Ram Prasad]

Hi Ranchers,

I am trying to write a function for factorial calculation. When i pass number more than 160 as input and trying to get the factorial, the return is Infinity

I am using a double literal to store the data and input is passed as integer n . I have taken the recursive approach

could someone suggest what data type i can use in order to get the factorial even for bigger numbers or correct me if i need to use other mechanism

My code looks like

 
public double fact(int n) {
		if (n <= 1)
			return 1;
		else
			return n * fact(n - 1);
	}  

Thank You
ARP

[Henry Wong]

Take a look at the BigDecimal and BigInteger class.

An infinity value for double means that you exceeded the upper range for the type -- except for infinity, that is.

Henry

[Rob Spoor]

BigInteger is the way to go.
There is also a class called BigDecimal, but you shouldn't use that for whole numbers.

[Pawel Nowacki]

Also you may take a look at Fast Factorial Functions
Looks like its not so simple after all ... They discourage using "simple" recursing method