lemma
proved
tactic proof
partialDeriv_v2_const
show as:
view Lean formalization →
formal statement (Lean)
39lemma partialDeriv_v2_const {f : (Fin 4 → ℝ) → ℝ} {c : ℝ} (h : ∀ y, f y = c) (μ : Fin 4) (x : Fin 4 → ℝ) :
40 partialDeriv_v2 f μ x = 0 := by
proof body
Tactic-mode proof.
41 unfold partialDeriv_v2
42 have h_const : (fun t => f (coordRay x μ t)) = (fun _ => c) := by
43 funext t
44 rw [h]
45 rw [h_const]
46 exact deriv_const (0 : ℝ) c
47
48/-- Second derivative `∂_μ∂_ν f(x)` as iterated directional derivatives. -/