what is wrong with my recursion code?

Question

I have a recurrence series so i have converted into recursion form. But it will show as maximum stack size reached.

The same code is working with n=4 as fn(4) and working correctly but not working with higher values. what is the problem with higher values such as n = Math.pow(10, 18)

var fn = function(n){   

    // take initial value of f(0) = 1 & f(1) = 1
    if(n===1 || n=== 0)     return 1;

    //calculate on basis of initial values
    else if (n === -1)  return (fn(1) - 3* fn(0) - gn(-1) - 2* gn(0));

    else
        return (3*fn(n-1) + 2 * fn(n-2) + 2* gn(n-1) + 3* gn(n-2));
}; 

var gn = function(n){

        // take initial value of g(0) = 1 & g(1) = 1
        if (n === 1 || n === 0) return 1;

        //calculate on basis of initial values
        else if(n === -1) return ((gn(1) - gn(0)) / 2);

        else return (gn(n-1) + 2* gn(n-2));
    };

Answer 1

The problem with higher values, such as n = Math.pow(10, 18) is that the stack is simply not that big. (Not even close.) You can usually have a stack depth of a couple thousand, and not much more.

You should use iteration instead.