Thread: question about recursion..

public class Recursion {
 
   public static double power(double a, int n){
double tmp,result,answer;
 
       if(n % 2 == 0){
    tmp = power(a, n-1);
    result = (tmp*(n/2));
    answer = result * result;
 
 
    return answer;
}
 else if (n % 2 == 1){
    tmp = power(a, n-1);
    result = (tmp*((n-1)/2));
    answer = result * result;
 
 
    return result;
 }
 
 
       return 1;
 
}
    public static void main (String [] args){
        double tmp;
        tmp = power(2,10);
        System.out.println(tmp);
    }
}

it keeps printing 0...

its supposed to print 2 to the power of 10 but i dont know what im doing wrong..
its supposed to be, if n is even solution would be

a^n = (a^n/2)^2 if n is even
a^n = (a^((n-1)/2))^2 if n is odd.... any comments? thanks..

I'm a little surprised that code doesn't result in a stack overflow (it looks like it should from visual inspection).

In a recursive algorithm, you must check for the base case(s) first. I don't see a base case before the recursive call, thus you have infinite recursion.

What's the base case? It's when n=0.

Additionally, I think you're recursive logic a little incorrect.
a^n = (a^(n/2))^2 if n is even
a^n = a*(a^((n-1)/2))^2 if n is odd

Lastly, you're code implementing the recursion calls are off.

You're calling power(a,n-1), but the recursive logic requires a^(n/2), not a^(n-1). This needs to be fixed for both the even and odd cases. Also, that strange multiplication by temp*(...) stuff needs to be removed.