Different algorithms to calculate Fibonacci number

fib.js

// Fibonacci
// n = 1 2 3 4 5 6 7
//     1 1 2 3 5 8 13...

// O(K)

var fibc = function(n) {
	var sqrt5 = Math.sqrt(5),
		phi = (1 + sqrt5)*0.5;

	return Math.round(Math.pow(phi, n)/sqrt5);
};

// O(N)

var fibn = function(n) {
	if (n < 1) {
		return 0;
	}

	var i = 0,
		j = 1,
		k = 1;

	for (; k < n; k++) {
		j += i;
		i = j - i;
	}

	return j;
};

// O(Nˆ2)

var fibr = function(n) {
	if (n <= 2) {
		return 1;
	}

	return fib(n - 2) + fib(n - 1);
};