GMP (arbitrary precision library) implements it as a lookup table for "low" n but uses a different set of identities for larger n. http://gmplib.org/manual/Fib

GMP (arbitrary precision library) implements it as a lookup table for "low" n but uses a different set of identities for larger n. http://gmplib.org/manual/Fibonacci-Numbers-Algorithm.html http://gmplib.org/manual/Fibonacci-Numbers-Algorithm.html