English
The Frobenius norm of the matrix obtained by replicating a row vector v along rows equals the Frobenius norm of the vector v interpreted in the L2 sense.
Русский
Норма Фробениуса матрицы, полученной повторением строки v по строкам, равна норме Фробениуса векторa v в смысле L2.
LaTeX
$$$\|\mathrm{replicateRow}_{\iota} v\|_{F} = \|\mathrm{toLp}_2(v)\|.$$$
Lean4
@[simp]
theorem frobenius_norm_replicateRow (v : m → α) : ‖replicateRow ι v‖ = ‖toLp 2 v‖ :=
by
rw [frobenius_norm_def, Fintype.sum_unique, PiLp.norm_eq_of_L2, Real.sqrt_eq_rpow]
simp only [replicateRow_apply, Real.rpow_two, PiLp.toLp_apply]