https://en.wikipedia.org/wiki/Exponentiation_by_squaring https://en.wikipedia.org/wiki/Exponentiation_by_squaring https://en.wikipedia.org/wiki/Fibonacci_numbe

https://en.wikipedia.org/wiki/Exponentiation_by_squaring https://en.wikipedia.org/wiki/Exponentiation_by_squaring https://en.wikipedia.org/wiki/Fibonacci_number#Matrix_form https://en.wikipedia.org/wiki/Fibonacci_number#Matrix_form Faster Haskell implementations exist as shown on the Haskell page link, but the idea was to show the most straightforward form that is also recursive with an order of magnitude better runtime.