On Mon, 18 Apr 2022 at 14:30, GUSTAVO TERRA BASTOS <[email protected]> wrote:
>
> Hi guys.
>
> Given two n x n matrices M, N, we know it is a big problem to find the 
> positive integer "i" such that M^i = N (There are other hypothesis involved). 
> In my particular case, I would like to do the same for 3 x 3 matrices M , N 
> over F_{11^2} (finite field with 121 elements).

Note that finding this integer i here is something different from what
is usually referred to as the "matrix logarithm" (the inverse of the
matrix exponential) which gives a matrix rather than an integer as the
result.

Is it prohibitive to just compute powers of M until you find that M^i = N?

Any i would need to satisfy det(M)^i = det(N) which should be faster
to solve for large i unless det(M) and det(N) are both zero or one.
Otherwise I think you can generalise the approach to other
coefficients in the characteristic polynomial.

Oscar

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