While playing around with the Fibonacci series. I found a way to compute nth Fibonacci number in Log(N) complexity.

In the excitement, I searched on the net if the algorithm has been derived before. I found out that the algorithm is called as Fast Doubling algorithm. I looked into its derivation and all of them followed the same method using matrix exponentiation.

My method is simpler and intuitive and could be used for self derivation.

I wrote a medium blog regarding this. Thought it would be helpful for someone.