mathlib3

094b1f51 - chore(*/matrix): order `m` and `n` alphabetically (#13510)

chore(*/matrix): order `m` and `n` alphabetically (#13510) In a few places this also reorders `(n) [fintype n] (m) [fintype m]` to `(m n) [fintype m] [fintype n]` which seems to be where we prefer to put typeclasses.