A useless thing that i think it could help some people

Revision en3, by myanhcute, 2024-12-02 18:46:06

If there is a problem like this: Give $$$4$$$ integer $$$a, b, c, d$$$ and $$$u_n=au_{n-1}+bv_{n-1}, v_n=cu_{n-1}+dv_{n-1}$$$, we knew $$$u_0, v_0$$$. We need to calculate $$$u_n$$$ with $$$n\le 10^9$$$. This problem can be solved by using matrix exponentiation, we have $$$u_n=(a+d)u_n-(ad-bc)u_{n-1}$$$ with $$$n>1$$$.

My fast proof

sorry for my bad english

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en4 English myanhcute 2024-12-02 18:46:14 0 (published)
en3 English myanhcute 2024-12-02 18:46:06 35 (saved to drafts)
en2 English myanhcute 2024-12-02 18:45:39 0 (published)
en1 English myanhcute 2024-12-02 18:45:16 402 Initial revision (saved to drafts)