Square root of a number using log

For a given number find the square root using log function. Number may be int, float or double.

Examples: 

Input  : n = 9
Output : 3

Input  : n = 2.93
Output : 1.711724

We can find square root of a number using sqrt() method:

3.464102 

Time complexity: O(log₂n), for using sqrt() function.
Auxiliary space: O(1)

We can also find square root using log2() library function: 

3.464102 

Time complexity: O(log₂log₂N), complexity of using log(N) is log(logN), and pow(x,N) is log(N), so pow(2,0.5*log(n)) will be log(logN).
Auxiliary space: O(1)

How does the above program work? 

 let d be our answer for input number n
 then n(1/2) = d 
 apply log2 on both sides
 log2(n(1/2)) = log2(d)
 log2(d) = 1/2 * log2(n)
 d = 2(1/2 * log2(n)) 
 d = pow(2, 0.5*log2(n))