Regarding the computation of a single term: No, the well-known Binet formula involving phi is unsuitable because it uses real numbers. See these detailed comme

Regarding the computation of a single term: No, the well-known Binet formula involving phi is unsuitable because it uses real numbers. See these detailed comments about handling quadratic surds properly, which is effectively the same as the fast doubling algorithm: - Chinjut: https://news.ycombinator.com/item?id=9316574 https://news.ycombinator.com/item?id=9316574 - xyzzyz: https://news.ycombinator.com/item?id=9316144 https://news.ycombinator.com/item?id=9316144 Regarding the computation of F(0) through F(n): No, this is not true either. The matrix method and fast doubling only compute O(log(n)) terms of the sequence, not the complete sequence from 0 to n.