English
For p a matrix of polynomials, the coefficient at position i,j,k of matPolyEquiv.symm p equals the coefficient k of p at i,j.
Русский
Для p — матрица полиномов, коэффициент k в позиции i,j после применения symm равен коэффициенту k в p на позиции i,j.
LaTeX
$$$\\text{coeff}(\\text{matPolyEquiv}.\\mathrm{symm}\\ p\\ i\\ j)\\ k = \\text{coeff}\\ p\\ k\\ i\\ j$$$
Lean4
@[simp]
theorem matPolyEquiv_symm_apply_coeff (p : (Matrix n n R)[X]) (i j : n) (k : ℕ) :
coeff (matPolyEquiv.symm p i j) k = coeff p k i j :=
by
have t : p = matPolyEquiv (matPolyEquiv.symm p) := by simp
conv_rhs => rw [t]
simp only [matPolyEquiv_coeff_apply]